I would say that with the loaches, a rainbow shark will be to aggressive. They are smaller sharks, but still a bit aggressive
Whether or not you are overstocked will depend on filtration, partial water changes etc, so some details on those would be ideal
Rams are great. You must be careful with your water paramaters. They can be very senstive to bad water quality. If you have your heart set on rams, why not go with bolivian rams. While they are not ultra hardy, they are definatly easier to keep. A pair of these would be nice
Red phantoms would also be nice. Rummynose tetras are gorgeous tight schoolers and their red noses are beautiful. I have rummies and they look amazing.
If you fancy something that is easy to keep, you could get a group of MALE platies. While they do not shoal, they are avaliable in a wide range of colours and can look quite cool!
It's really personal choice though.
My ideas overall are:
Bolivian Rams (As an alternative to blue rams - it is up to you, but these guys may be easier
)
Rummynose Tetras
Red Phantom Tetras
Cherry Barbs (A hardy schooling fish - they do not hang out together as much as many species but they need company - very attractive small fish)
Platies (Males - Females and males will overpopulate your tank!!!)
Hope this helps
