Yes, the best powers, see through walls earth & stone, and walk through most dungeons completely, are at will, duration of 3+ con rds, and a standard action to activate. 30' range isn't anything to sneeze at, IMO, and enemies shouldn't be able to detect you back, as they'll often have no line-of-sight or effect. Regarding Earth Glide, your movement rate is your only limitation.
Almost everything in 'standard' D&D is made largely from either earth or stone. Just travel underground like an Earth Elemental. Just watch out for bulettes. They'll try to get you to buy Insurance.
You just don't have to deal with doors, or even stairs, if you don't want to. Plus, you should get a free +2 Circumstance bonus to listen checks while inside a solid object, just like an incorporeal critter, since you're still within a solid object, which conducts sound better. With Mobile Spell-Casting Feat (Req's 8 Concentration. That's it; no other prereq's) you can come up through the floor (perhaps even down from the ceiling; ask your DM), cast, exit stage floor again. Scout like a earth elemental, but with almost perfect trap vision; stone doesn't impede your vision at all. You can see secret compartments, hidden caches, buried treasure, all sorts of mechanisms and otherwise hidden stuff. Get Darkvision somehow!!1!i.
