Jon and I both run local D&D games, he has his awesomely weird World of Alidor and I have my all-fighting-all-the-time Wild Times campaign. Both of us use miniatures and a Chessex mat to take full advantage of all the fiddly bits in the 3.5 combat system, with its AoO's and 5-foot-steps and whatnot. But there's one big difference in our set-ups: I use a Battlemat (measuring 26 inches by 23 inches) and Jon uses a Megamat (34" x 48"). His mat pretty much covers the entire table and much of our other game periphenalia sits on top of it, but even so the actual playing field for our little plastic and metal dudes is much larger than the little almost-square sitting in the middle of my table. The size of our playing fields has a noticeable affect on combat. In his game spell and weapon ranges are much more critical and you need a lot more movement to close with an enemy. My game is far more forgiving on plateclad melee types. Admittedly, we both end up exacerbating the differences. I treat my mat as the battle screen on an old computer game; any movement off the mat counts as 'escaped' like we were playing a tabletop version of Ultima IV. Meanwhile Jon is perfectly willing to say things like "the enemies are approaching you from 200 feet from the map edge". You can get away with only carrying an axe in my game, but in Jon's game you best be carrying a bow if you don't want to miss out on a LOT of combat. I'm seriously considering a Barbarian/Scout for my next Alidor PC, partially for all the extra movement (an partially because I've been reading a lot of Howard lately). Meanwhile, in my campaign Pat's 'speedster' half-elf was wasted on my tiny tactical display.
I'm now seriously considering getting one of the larger Megamats and alternating between the two sizes from session to session, to try to balance out the relative advantages of light infantry/archers/artillery versus the tanks.