It is difficult to id the plants because of the glare in the picture. But your pool area seems to receive a lot of direct sunlight.

A variety of plants would succeed here. Do you have a specific preference? My preference would be to plant succulents in these pots -- low maintenance and they look quite pretty. Also they will not shed leaves frequently so you do not have to clean up the pool area.

I'd guess that the taller plants are Cordyline australis, but the trailer isn't of enough detail to identify on my monitor. Take another shot as a close up if you want a good chance of identifying this. I would take a stab at guessing the trailer as possibly being a white flowering Bacopa. As to suggestions for alternative plants, it would help if you said what town you are in, or at least what Sunset zone. Also, container planting suggestions will depend on whether you have these hooked up to automatic irrigation or not, or how often you care to hand water if they aren't hooked up to irrigation. Succulents can be an excellent starting point for container, and there is a huge variety to select from; but not all are equally hardy or tolerant of full hot sun.

I think they are Beaucarnea's-Ponytail palms. Two in the left pot,and two in the right.