Ross and Kim -
Depending on where you are at with your loan to value, it may or may not be a good idea. I am a Realtor in Hart, so I know the area very well. I can tell you that there are a lot of modular homes on the market right now, many of which are in foreclosure. If you have a lot of equity in your home, and can afford the improvements, it may make sense to add some touches that will make your home stand out above the rest. How soon you need to sell will also play a vital role in whether or not you should put any more money into the home. Ginger made a lot of really good points, most of which I would agree with. I would likely avoid the hardwood floors, and finishing the garage likely won't net you any returns. The finished basement may offer you an edge. I typically start my discussions with potential sellers by asking these important questions:
Why do you want to sell? How soon do you need to sell?
The answers to these questions help determine the next step. My profile is here on Trulia, and I would be glad to meet with you in person and offer any advice I could give.

You know, most realtors will tell you to talk to a local realtor. This is one case where you really should. I would talk to a few realtors and tell them the truth: You are not ready to sell but want their view of what should be done to get ready to sell. I would ask them specifically about how modulars are selling and ask them who handles financing for modulars locally. A bank that I have dealt with has recenty stopped offering financing on modulars and if financing is an issue, that may affect your price. It probably is not an issue, but I would ask the local realtor a lot of questions.
I have done remodeling and new construction. So I will give you a Seller's perspective. In general no, it is difficult to recoup an investment. In particular, you need to make sure that you do not overimprove a modular home. Improvements represent a larger percentage of home value on lower priced homes and that can make it proportionately more difficult to recoup. There is one major caveat: if you are handy and can do much of the work yourself, it may be worth your investment. And fresh paint in neutral colors will bring you a positive return.
You asked about a wood floor: If the home has no flooring at all (you mentioned that it is a year old), then I do think that you need to put flooring down to sell it. It is more difficult to sell a home that is not finished, so I would put flooring down. However, I am not sure that I would invest in wood flooring for a modular - again it depends if the values in your area can support it.
Also, you need to determine if you CAN put in wood flooring. Is your subfloor OK for wood flooring and is the rest of the house set up for the 3/4" thickness of the flooring? Can you join the wood on a level basis to other floors and will all the doors clear? If not, I would consider pergo or other wood laminate floor. This is thinner, can go over most subfloors. It goes down fast and you can definitely do it yourself. Some are very nice looking. This is a much less expensive alternative and I think you will recoup your investment.
Re: finishing the basement. Buyers love a finished basement. Again, if you can finish this yourself with paneling and vinyl or laminate flooring, it will help to sell the house. But basement space is not valued as much as above grade space and if you hire a contractor, I don't think you will recoup it.
I would not finish the garage. This is expensive and buyers do not understand the value of it. It is expected and I do finish them in a high end house. But for the low to mid price homes, the real value is in having a garage, not in finishing it.
Well, you are on the right track by asking questions but I would discuss all of the above with a couple of local realtors. Hope this helps.