New garage speaker placement?

No. Haha, i wish. But, i'm planning a similar space.

http://www.12-gaugegarage.com

I want to fill the room but not sure where to put speakers. I have in celing speakers throughout my house now. I have heard that putting them in wall sounds better than ceiling.

If this a system to listen to while you work, maybe some powered monitors would be the best way to go. They can be placed on a shelf or mounted to a wall. No need to fool around with an external amp. You would just need a source with a volume control. (ipod, tablet, notebook, etc...)

Yeah, never thought about those. What brands should i look at?

Your best bet is to go to a music store, like Guitar Center. They have brands like KRK, JBL, Tannoy, Adam, Mackie, M Audio, and probably some others I'm forgetting. To be clear, I'm not saying these type of speakers will be as good, or better than traditional audiophile gear, but for a garage where you won't be doing any critical listening, they should work nicely. I have a pair of Tannoy 502's I use on a computer. I know they make a larger one with an 8" woofer. For your garage, those would probably be best.

If you are willing to hang speakers on a wall instead of using within wall types, and for $500 and something that will sound nice:

Pioneer SP-22lr speakers ($129),
Pioneer A-20 amplifier ($270),
Pioneer makes a subwoofer that mates with the SP22s (i believe ~$130).

All values retail.