I actually go back WITH my ex and our daughter (this fall will be the 5th time since we split, weird - I know), but my advice is:
- you can definitely do it. Had my situation been different, I would have still continued to go, finances-willing, without him. With kids under maybe 6 y.o., I imagine I would have appreciated another adult being there (a friend or mom or older niece/nephew even), but after that, no problems. Your children are definitely old enough to not need constant care.
- I would recommend the first time be under different circumstances than your "usual" was as pre-divorce. I can't imagine Disney ever being tainted entirely, but I see the benefit or creating a new normal. It sounds like your resort will change and that's a good thing. And your children will be older, which means new things will interest them and make the vacation different than past ones anyway. These are new memories!!
-That being said, don't be afraid to talk about old memories, too. If you enjoyed time there together before, acknowledge it. It's good for you and for them. Just don't let those thoughts dominate your mind and you'll still feel the magic.
Go for it!