compatibility question

those fish should all be compatible, but part of stocking is making sure that all levels of the water will have fish, so that they all have their own areas to move around in. i would go with the betta, tetras (around 6) or 4 of one kind in your list, 4 of one other kind you have listed, and 3 cory cats (all same kind) for the bottom of the tank. i think that having more fish of fewer types makes the tank a little less hectic. someone else will have a different opinion on what makes a tank nice. if you get the neons, don't get the betta, or vice-versa. in my experience they will nip fins like there's no tomorrow, and damage the betta.

i noticed that this is your first post. . . you should read the thread on cycling in order to prepare your tank for the fish. it's in the newbie forum, one of the first few threads on top.

I think you have a pretty good mix there - lot of different varieties/colors you can choose from with the platys, mollies and guppies....If it were me, I would pass on the swordtail - they can be nippy sometimes, and you have a lot of tempting finnage there...the betta should be ok, although they can be actually shy sometimes in a community setting - it depends on the individual betta...hit or miss. Zebra danios would also work...cherry barbs are nice....you also have the option of many other tetras. Get some cory cats too! Have fun! Take your time cycling and stocking the tank - don't pack em in too tight, although I appreciate that you are starting out with a good size tank for the fish you are thinking about. Good filtration, water changes....cool "aquascaping"...take pics as you go and share them! Best of luck to you!