I only do carry on. Except my last cruise because we drove so we way over packed. Our last trip to Disney we had one carry on, and each a personal item. It was fine, we had lots of room. I take travel sized items we can leave behind (like toothpaste and small sunscreens or shampoo/conditioner). I will say we don't buy a lot of stuff any more, and when we had the Disney magic of the checked bags showing up in the room I would check one just because it was a fun surprise, but it's kind of a pain. We tend to pack clothes that dry fast, neutral colours to mix and match, and always two or more swimsuits. We pack sandals and wear our running shoes, that's usually good for the parks.
For the liquids, last time I did what I always do in the security line and put both in one bucket with some other small things and then got yelled at by the security guy and told to separate them next time. We were flying to Toronto then Orlando and I've never had that problem before. Oh well. I have some refillable containers so use those for sunscreen mostly. I tend to use the shampoo the hotels offer, but take some conditioner.
The longest trip we've done with only carry on was a pre cruise hotel night, 7 night cruise, and two nights at Disney. That was only tricky because of needing certain dress up clothes for the cruise. Disney by itself is much easier.