Hmmm. Never heard of Rockville. If you're in Greenville, Texas, you're too far from Dallas to come into town just for shops/eats. If you're on Greenville Rd., you're close to everything.
If you want to check out a great shop for gear, go to MotoLiberty. Near Royal Ln. and I-35. Strokers is not too far from there. Bunch of Victory bikes and the new Royal Enfield, plus the odd custom and Harley. General bike hangout. For classic bikes, stop by Big D Cycle. Also in the general vicinity. Sometimes they have some cool stuff for sale in there, sometimes nothing going on. Hit or miss. But just between those three, you could waste a good afternoon and not drive all over town.
Lucille's recommendation's are good. Only go to the original Sonny Bryan's on Inwood, though. Lockhart Barbeque on Bishop is the best for brisket. If you're on Greenville, it's loaded with restaurants and clubs. Cheese fries at Snuffers are a must. Get em loaded. Heart attack on a plate!