Love blue tiles. Depending on how much sun and how hot your pool gets in the summer should dictate what color it is. We live in Arizona, so cool blues work best. Our neighbor has brown tile and a dark pebble tech pool. Looks like a swimming hole and gets really hot - 94% water in the summer. They obviously didn't think it through.

Normally a hot tub comes with a means of heating the water, and maintaining it without having to empty the water. This is where water filtration and disinfection methods are worth it and less wasteful. It really doesn't matter whether it is stainless steel or not: you are heating up water to levels that naturally promote bacteria and algae. Hence the NEED for some type of disinfection - which can range from tossing in a chlorine table to add ozone or other types. I suggest you purchase a book entitled "What colour is Your Swimming Pool" 2003 edition. It will give you a practical guide to what you are looking for to maintain your spa tub and why you need to do it.

We have had a vinyl lined pool for 15+ years - you are making a good choice. They need no maintenance or resurfacing etc. Ours is an Aqualux liner in Caribbean. http://www.aqualuxpool.com.au/colour-range/ This colour is just the right amount of blue/green to sparkle and shimmer, look cool and inviting, but dark enough to gather and retain the sun's heat. I ran a swim school for many of those 15 years, and needed a pool that could take the knocks of hundreds of children each week, and look like something they wanted to dive into. Any lighter and the pool would look too cold, and darker looked scary! I have friends who chose the darker colours for their heat retention properties but the pools don't look as inviting, and algae builds up quicker but is harder to notice until the levels are quite high, so needing more chemicals to control/eliminate.