I can't imagine two moons colliding that close to our world would leave it unscathed. Also lunar collision is pretty exciting and pretty damn interesting. I don't know what would happen if they actually did collide, it's not important, just the tension of the suspense is what I'm looking for. Can make for some interesting stories.

All three of those planets sound really great.

My concern is getting like 4 or 5 or 6 observable (with naked eye) planets so we'd still need one more, maybe a couple of gas giants? OR a big Ice planet. Then we can leave any further planets in the system for later or for people to put in on a by need basis.