It depends on how you treat your car. There is going to be sand on the road between the first snowfall of the year (early October) and late April. If you don't mind a new paintjob every few years you could get a few good days through October.
Between late April and mid-September, if its not raining you are good to go (and it doesn't rain often or for long durations). The upside is that during the summer the mountains offer some great drives that are less than 30 min from Denver.
As far as neighborhoods, if you are looking to buy a new house: Aside from the areas you've already mentioned, the "Westwoods" area of western Arvada is under development and should give you what you want in a community in your price range. Its also adjacent to areas that have been developed for some time so accomodations are readily available. Just something to look into.
Good luck convincing your wife
