I haven't recorded a lot, but all I did was always from the first row or front of the stage, the place I prefer to be during shows otherwise too. Maybe it's not the best place to be soundwise, but I've had good results mostly. Probably because I've only taped smaller gigs; I guess the bigger the venue, the more difficult it gets.
Most important thing for me is to not let the recording process take away my enjoyment of the show. I wouldn't stand somewhere at the back where I can see fuck all just because it's the best place soundwise; I'm not that dedicated.
I don't know enough about microphones etc do give you advice on what to buy, but this is a useful site
http://taperssection.com