I actually work in this area and there is a nice park (Terry Hershey Park) with a paved trail just off of Memorial. Round trip, I think you can easily ride 20 miles or so. The main problem though is that it is multi-purpose - or in other words, you will encounter lots of walkers, joggers, families, etc., so it can be frustrating to ride there if it's a nice day. But, this area is growing rapidly (lots of construction), so riding on the roads is not easy either.
That being said, there are usually plenty of organized rides and weekly rides put on by the LBS's that are fairly close by and will get you away from too much traffic. I ride with a group that trains for the MS150 every year and they usually have drop-in rides throughout the year, so let me know if you're interested - the location varies, but there are definitely some places that aren't far away where you can always count on finding somebody riding. I've been off my bike for several weeks, but I'd love to get back out there, so let me know if you want to ride when you get here!