I live and work in the Herndon/Reston area. Whether it will suit you depends on what you're looking for. For example, I had a completely different reaction to South Riding, which I also visited when house-hunting. Two words came to mind and wouldn't leave after I went to that area -- "suburban hell." Street after curving street of all kinds of housing units, with access to the "real world" in the form of a route out of there very difficult to find. But obviously a great place to live for someone looking for something other than what I was.
Herndon, let's say the east side of it anyway, the side nearer to Fairfax County Parkway/7100, has a small-town feel to it (something that I prefer), with a lot of communities dating from the 80's, and some parts considerably older. Mostly nice, safe neighborhoods (and a couple less nice & safe) that nevertheless don't feel cut off from the rest of the town. The side of town closer to the airport is more built up, more condo/apartment housing, some taller buildings, big shopping center with stressful parking lot (can ya tell I'm a small-town girl?). I prefer the east side.
Reston is a little weird. (You can Google it, maybe check Wikipedia.) Some people love it, others hate it, few are indifferent. It has grown up quite a bit in the central part over the last decade or two I guess, with some highrises and a Town Center (big mall) with what I consider to be fairly ritzy stores. Reston's housing seems to me to date mostly from the 70's (at least what I've seen of it), and the less expensive homes look pretty dated and tend to not have garages or even driveways. There are also some really beautiful communities with lots of trees, some with lake views -- they are pretty pricey. Some people like the original Reston design which was intended to let you walk anywhere you needed to get in town -- I think there's a shopping center in walking distance of every community; other people hate what they see as a 1984-ish uber-planned town.
Herndon is in general more affordable -- a general principle along this corridor is the further east you go the higher the prices get.
Search online and if at all possible visit in advance and take a drive through communities you are interested in. Nothing beats seeing it in person. Also, try to get your hands on local papers -- you can check out where crime is being reported and where other problems may be going on. This was immensely helpful in convincing me to go as far east as I could afford (predictions of severely worsening traffic along hwy 7) and eliminating one Herndon neighborhood from consideration (I forget the name of it but it's off part of Alabama Dr./St. whatever).
House-hunting...
