I haven't read through the other responses, but I'm a decorating show fan and I tend to go with the whole neutral wall thing myself. I do love color, but not on my main floor. I save the color - and I love what you describe (from your aquarium) for my bedrooms. That whole seaside/water theme - is our kind of bedroom scheme.
Our main space is all neutral. In this day and age where a lot of rooms run into each other with open concept or you can see down one long hall, if they don't flow, then it chops it up and looks smaller than it is. So my personal thought is - if it can't all be the same color throughout (like a a neutral - to tie it all together, and the lighter the better to brighten it up) - then shades of the same family works really well. what's your favorite room? Is it the kitchen? If so, then if you could bring some of that in - like the grey? and then swap out some of your cushions (or just make/buy a few toss cushions in the same yellow as kitchen) to bring it together.
Terracotta and mustard look lovely in some homes - we had in our last home, but if you're looking for fresh - especially where you have the dark floors and couch, I'd go light.
If you want ideas of what looks good for paint - you can go to Benjamin Moore website, and they have a tool - and you can put in a color (doesn't have to be a wall color) but say black - and they will tell you what looks good with it. They'll even give you a trim color, etc. We did that our whole home. Worked very well and then - you can pick shades that go with the colors you picked, in the same family, if you want to carry the look throughout etc. It makes it easy without hiring a decorator. Or just use it for ideas. It will show you what a color will look like in a bathroom, a bedroom, living room, exterior, etc.
Good luck :)