Outside Coachella I don't catch a ton of shows but this year Ive already seen a wide number of the acts. Here's my assessment, please add yours.

Phenomenal

Janelle Monae - cross James Brown w Grace Jones with Prince w Meatloaf and you'll get the idea - one of surest things on lineup
Foals - Just an onslaught of technical musicianship and those Total Life Forever anthems rage live. My vote for very best show of 2011 fest.

Damn Good
Franz Ferdinand - Kapranos the real deal and so many of their songs just have pop
Grinderman - My Favotite of Nicks too incarnations but this is really Warren Ellis shoe. A Masters class in guitar pedal distortion.
Nick Cave and Bad Seeds - not as immediate as Gtinderman but massive body of work.
Vampire Weekend - sucked at 08 Coachella but they've reach a Coldplay like competence live now. Very Good Energy
Violent Femmes - A blast lest time I saw them, but that was 1990
Yeah Yeah Yeahs
TEGAN & SARA - Voices really pop live

SOLID
Lou Reed - Saw Lou Three Timex in 80s and 90s always good never great...hold out very little hope for this set but wont miss it.
Grizzly Bear - Sound great but stiff everything played to track zero spontaneity and as bad as they get with stage banter.
Hot Chip - Fun but have never blown me away
Spiritualized - Like Grizzly Bear a fine musician but stiff performer good but an overrated act as far as reputation on this board goes.
TAME IMPALA - problem is guitarists cant play everything live - hes impressive but rest of band isnt

BETTER ON RECORD - great albums or songs but don't have it live
Pheonix - songs just don't do anything for me live
Modest Mouse - seen many times very inconsistent
Beach House - sound good but sleepy as fuck
The XX - see Beach House

Almost As Bad As MGMT
Smith Westerns - zero Charisma
Passion Pit - They don't mail it in like MGMT but watching lead singer sing is a genuinely disturbing site