I've been playing with my friends a lot lately and I find that it would be helpful to have at least one tank in our group to help take some damage off of them. I tried out Galio earlier, but he just felt strange to me. From what you guys have seen who is a pretty good tank champ for dominion play? Or should I just choose a champ that is a beefy dps char? I was thinking Shen for his ability to teleport to a fight just like that, but I don't wanna blow my IP on him and then just hate him.

Alistar is a solid pick.

Cho'gath is pretty good as well, as long as you don't go 100% tank on him.

Maokai is great but most likely you'll be on bottom lane all game.

In that case have you tried Leona?

I haven't played her in Dominion but after playing against/along side her she definitely contributes to team fights. Gap closer, 2 stuns, aoe nuke, and super tanky.

Why not just play a tanky dps champs and just build more tank and less dps?

Most of the pure tanks like Alistar/Leona/Amumu/Galio are pretty bad on this map since their kits are designed for 5 v 5 fights