Ive never been to a UFC event. I have however been and watched Cage Rage (an english mma promotion) at earls court here in the uk. I paid £75 for my ticket which got me a mediocre seat. From my experience you would have to be near enough ringside to get a proper view. I was sitting reasonably close yet chose to view the big screen as you cant really see much from the stands. You cant really tell if punches land, nor can you see the intricasies of submission grappling (other than full on, blatent arm bars. Interesting side note, a guy got his arm broken yet still fought on to win a decision that night). Anyway, I personally preffered a UFC broadcast any day, it costs a fraction of the price and you get a much better view of the fight. Saying that if it was a UFC event I would have had the bonus of seeing some of my favourite fighters, which would have been awesome.
Heres a short answer, it really is the closer the better, I would reconmend as close to ring side as you can afford.