I would never allow them to share a family suite! That's just crazy. If they want to go, and you are ok (ish) with that.. be sure they
fully pay their own way. Have times that you have the boys, then times when they have them, and maybe a couple of times together if you're comfortable with it.
Most of this depends on how your relationship is with both, your ex, and his wife. Don't let him guilt you into anything you're not comfortable with. You can always explain to the boys that although you would be fine with their dad and wife going to Disney, they just couldn't afford to do it right now.
I take my daughter to Disney every year. This year her dad announced he'd like to come down so he could experience it with her. If we were staying in a hotel room, I would have told him he would need to get his own room, but because we will be renting a 3 bed/3 bath townhouse, I agreed to let him stay. He wanted 4 nights, I said no to that. 2 nights was all I allowed. It's my vacation too and I didn't want nearly a week taken up with him there. He will be there 3 full days since his flight lands at 9:20 am and his flight out leaves at 8:30pm. I booked his flight and got him great rates, and I will arrange his tickets (he's not good with stuff like that), but he pays for everything that is for him (I've paid everything for my dd and don't expect him to pay anything for her).
His girlfriend will NOT be coming. If he wanted that I would have a problem with it. If it's time with his daughter he wants, he doesn't need anyone else there with them (I will not be going to the parks with them, but I will be sharing 2 TS meals with them both).
Now if he was re-married, they would not be staying at the townhouse with us, but I wouldn't mind he she came down with him and they stayed nearby. And, BTW, my boyfriend doesn't come with us on vacation, though he does buy us our annual passes every year. He's ok with dd's dad coming for a few days. My bf and dd's dad get along great too.. alot better than me and dd's dad
Another important factor... we stay for 3 weeks. If this was a one week vacation I would not want anyone taking my time with my daughter. In that case, if her dad wanted to experience Disney with her, he'd have to manage to take her there himself.
You know your kids, your ex, and the relationship of all of you. If you're not ok with this, don't do it. You'll be miserable and uncomfortable on your vacation... and you're kids will see it no matter how much you smile. If they do come, SEPARATE ROOMS! And be sure they pay their own way.
Good Luck!