We manage a number of properties in both those zips and investors have seen excellent results in both.
We have found that, all things being equal, prospective tenants favor newer homes/neighborhoods over an equivalent sized property in a more established neighborhood, so your target zip codes are good choices from that perspective. Newer properties are easier from a maintenance standpoint as well.
I think that you will find a little more balance in the construction in Natomas with a blend of traditional single family, zero lot-line and town home construction. 95757 in Elk Grove has all of the above, but seems much more weighted toward traditional single family homes.
All things being equal, a property in 95757 will likely fetch a higher rent as the positive reputation of Elk Grove schools seems to be pretty widely known. However, it will probably cost more as well, (we don't buy or sell properties, just manage them).
In my opinion, the sweet spot in the market is a four bedroom home, with three being the minimum number of rooms I would recommend for an investment property. There is a considerable jump in rental price between a three and a four bedroom and a much smaller jump between a four and a five. Tenants will take a fifth bedroom if it is the same price or not much more than the four, but very few actually need the fifth bedroom. Finally, given a choice, I would avoid swimming pools. They increase expenses while fetching little or nothing in terms of increased rent. They can shorten vacancy times, but I believe the additional costs outweigh the benefits.
I suspect you have an agent already, but if you need a referral, I know a couple that have done a lot of business with investors in both areas. Of course, if you would like help renting out or managing the property over the long term, we'd love to talk with you. Good luck!