What are the best fish to start with in a tropical tank?

From a low-skill level tank owner...We have had great luck with Danios - they seem to be very hardy, and 4 of the original 5 we bought are still going strong after several years. Platys do pretty well, too, and are very inexpensive; they come in several different color varieties; make sure you have at least a 3 to 1 ratio of females to males, or else the males harr the females and they dont' last long. Pet store staff should know how to tell which are males. I only buy fish that eat regular tropical flake food I like to keep it simple. Our water is very hard [well water that goes thru softner salt], and has high pH - I just actually tested it for the first time, altho I've had the tank for 8+ yrs. It's just a casual hobby, and entertainment for our cats & daughter, so we don't want to spend a lot of $$. Petsmart has a nice system of labeling - we get only the "Tropical Community" types as they are non-aggressive; the tags also show level of difficulty for keeping, so we stick with "beginner."