@ChrisD. - if you’re after sunshine then Canary Islands aren’t a bad option. Plenty of resorts that cater well for young kids. I’ve been converted to all inclusive a of late. They work so well with young kids. Buffet eating works well as you’re not using up valuable sitting down time waiting to order food. My expectations have been well and truly managed with young children in tow!
I’m going to be harsh and suggest that you don’t bother with Disney or theme parks with an 18 month old. They will get just as much enjoyment being with you wherever you go, and simple things like digging in the sand will entertain for hours. Waiting in theme park queues fill me with dread right now. Flying virgin upper class would help - especially with a flat bed to sleep on. Saying that, there will be a lot of walking up and down the aisle and caged animal energy whatever class you fly!
In a few years we’ll head to Florida with ours I’m sure, but I think it’d be a bit wasted right now. Our daughter at 6 is probably just getting to the age where she’ll enjoy it, but I’m not sure she’d get on any of the decent rides.