You have received a very well-rounded set of answers. I also will try to add to the conversation rather than repeat what others have contributed. I want to add on to Michael's point because it is an important one for the out of town buyer looking for a wine country home.
Most realtors typically focus on a narrow geographic area. If the buyer is also narrowly focused this can work. However, most out of town buyers of wine country property will search a wider geographic base and are less locked in to certain locations, as you are when you say you are considering Napa or Sonoma.
As long as they stay within a hour or two of their bay area home, or an airport the specific town is less important. They are looking more for a setting, a certain type of terrain, views, privacy and proximity to great restaurants and other amenities. It is more about the experience and the quality of life they are trying to create, whether for a full time home or a weekend place. So having an agent who is sensitive to the vision, and can place the broader set of communities and possibilities in perspective, can be key.
I have had clients start in one area and end of in a completely unexpected (to them) place when they hit upon the right combination of setting and house. This is particularly true of country properties, as Michael noted. That is why an agent experienced in country property is critical so that buyers don't chase down properties not appropriate to their needs in terms of soil type (for horse property), amount and type of water (for agriculture or gardening), zoning or expansion possibilities-difficult to perc areas with wet weather ground water testing requirements that only have a two bedroom septic in place might be problematic for a large or extended family for example. It also applies to town properties, but more from an aesthetic point than a practical one.
I was able to secure a property for buyers from Berkeley when it fell out of escrow because the previous buyers and their inexperienced agent didn't think to assess whether the six bedrooms they ultimately wanted would be possible on the five acre site. This can't always be determined in advance but in this case it could have been. The previous buyers wasted a lot of time and money on inspections that could have been avoided. My clients are very happy because the property perfectly suited their needs without needing the six bedrooms.
And as many have said, finding the property is only part of the equation. I agree that many people put more effort in to finding a hair dresser than a buyer's agent and don't realize the benefits that a strong negotiator with good sales skills can provide them. This is particularly true in multiple offer situations which are common in our market. This week out of town clients of mine closed on one of the most beautiful properties I have had the fortune to be involved in, with redwoods and spectacular elevated views of the Russian River. We wrote an offer Day 2 on the market after I interviewed the listing agent to understand the sellers' needs.
The reason a good agent will do this is that often price is not the only factor that will get an offer accepted.
In this case there were three offers, two at full price, but my buyers offered a compelling set of terms that motivated the sellers to accept a price that was $23,000 less on a $580,000 home.
It wasn't just a case of a cash offer beating out those with a loan. We had financing but a good down payment, quick close and a flexible but advantageous rent back for the sellers. A good agent will determine the sellers' motivation and try to construct a win-win for the sellers on more than just price. As a listing agent I can't tell you how many times I have received offers on a listing without even a cover letter or a telephone call from the buyer's agent. Those offers can be at a disadvantage.
Anyway, I really ran on here but this is a subject I feel strongly about. I wish you the best in your journey and please let me know if I can assist in any way! The link below takes you to some articles I have written for buyers over the last few years.
I used to live in Sonoma and I can tell you, there are many part-time agents in the area who work on maybe three transactions a year. Kirsten is not one of them!
Interviewing a couple of agents is a great way to both find someone you are comfortable with and to also learn more about the home buying process. In addition to an experienced agent who knows the market and is great negotiator, it's important to work with someone who you communicate well with and can guide you as first time buyer thru the unknows.
I wouldsuggest that you interview a couple of agents until you fing one who you like ...it is really important to find a agent that listens to what you want first then give suggestions later.I know a lot of newer agents who will work on open houses they are also the ones that are hungry and are willing to go great measures for your satisfaction.I am a first time home buyer lender and work with many agents that are great but I really suggest that you find the person you like as opposed to having them referred to you.Thats just my opinion.Good luck and happy house hunting ....Jeffrey Martino Young at Essex Mortgage Bank in Santa Rosa. 1-877-870-2676 http://www.fhasubmissions.com.
Other things to think about besides the other comments, are will the agent have time to work with you and listen to what you want, are they willing to share references from recent clients, and what kind of business/transactions have they been working on recently. They need to know the market and have the connections and knowledge of upcoming properties to keep you ahead of the other buyers that are looking for similar properties.
Dave's answer is just right although I would add a few other suggestions. Make sure you chose and agent who is familiar with the market area in which you are interested. There are many different neighborhoods with broad variations in housing and amenities in both the Napa and Sonoma areas. I advise you to find an experienced agent, too....someone who can provide you with references from other clients. Finally, I'll echo how important it is to be comfortable with the agent you choose. It's a partnership you are forming. Confidence in your agent's abilities and a solid comfort level with their personality is essential to a good outcome.
Interview two or three agents and find someone you are comfortable with. You can find the two or three you want to talk to by reading answers to questions here to find someone that makes sense to you. I'm a strong believer in sticking with the agent you start with unless they fail to meet your needs, so you want to be sure to choose an agent you connect with.