I have never used it personally but have considered sand on a few occassions. I believe silica sand is the best type to use and it does look nice. My concern is with maintenance, compacting and other issues so I have avoided sand so far.
I think a dwarf gourami is an excellent choice for a 20 gallon. I have never kept rams or kribs but they seem to be small cichlids that are peaceful enough for smaller community tanks.
Some good possibilities include: danios, smaller barbs (there a few i think), tetras, livebearers (endlers, guppies, platies would be best for that size tank), kuhli loaches, and killiefish if you can find them. Killiefish are very nice looking and kuhli loaches will do a good job keeping the bottom clean.