If you like the idea of GT so much, why not keep blue acara? Much smaller than a GT and very similar coloration. They are usually peaceful, will be a lot easier to choose tank mates too. A Blue Acara, school of larger tetra such as red eye tetra, some cory cats, and 1-2 small-medium size pleco such as bristle nose or golden nugget, in my opinion will make a very interesting tank.
This is and excelent suggestion! Andinoacara Latafrons is available from right now from Tangled up in Cichlids if none are available locally. I haven't seen any A. Pulcher around for a while but I haven't been looking either. Thay are like GT lite, and absolutly beautiful someone suggested them I believe a couple of pages back. This would be an ideal fish for a 55 if you really like GTs. Actually there are many Acaras that would be an excelent choice if the OP is interested in ordering fish the options are vast if he's looking for somthing other than the typical chain store fair.