For gigs at the Entertainment Centre at Boondall, DH and I go for the Colonial Village at Taigum. It's not fancy, but it's cheap, clean and very family-friendly if you've got the kids with you - we stay in the villas but there are also standard motel rooms available. If travelling in and out of the city's not a problem for you, I can also highly, highly recommend the iStay River City a couple of blocks from Queen St mall - it is a little more expensive but the apartments are fabulous and the views are SPECTACULAR (if you're into that kind of thing - I'm usually not but it sure makes for an indulgent weekend when you wanna feel like a bit of a rock star!).
Good luck, I hope you enjoy the concert! x