I'm a guy who always attacks the TE position early. Once the top receivers have gone the field gets pretty equal quickly and I like to have one of the leading options at a fixed position. My thinking changes of course if the league does not feature a locked TE position although I'll still consider them, especially the likes of Gates and Tony G.
Outside of Gates there's not really anyone worth targeting early. If you get him it's a huge advantage but most leagues I've been in owners reach way too early for him. You can target other positions and still pick up a decent TE later rather than spend a 3rd rounder on Gates.
Once I have my 3 starting WRs, and if I still have a shot at him, I could grab Gates in the 5th. If he's off the board, I usually take my TE in the 7th or 8th round.
There is no TE really worth taking before the 5th besides Antonio Gates and Tony Gonzales. I usually wait if one of those two are off the board. You'd be surprised at the value you can pick up in that position late.
If you've already locked up 2 RB's, 1 QB, and 2 WR's, and Gates is left in the 6th, then go for him. Only other TE's to consider in the Top 10 Rounds are Tony G., Heap, Witten, and Kellen Winslow. I always wait untill the final rounds though along with my kickers (and I win all my leagues every year). Rookie TE's are easily forgotten about but can make a big impact (Owen Daniels anyone?). Greg Olsen is a top notch TE prospect and will make a big impact for a lackluster Bears Offense. He will battle Desmond Clark for playing time (another guy who can be a big late round steal for you), but never reach for a TE. Back-up RB or QB is always better then a TE (unless it's Gates). As for Kickers, you just need to wait untill the Final Round (or 2nd to last depending on what slot your picking in), and just grab a guy who is going to be on a great offense. There is no need to reach for Vinateri just because he is the best in the game. You can grab a Stephen Gostkowski late or even a Jeff Wilkins or Jason Elam. Matt Stover and Shayne Graham are one's to watch for as well.