Ive not kept Fire Eels before... they do get huge, but I have seen them well kept in this kind of tank. What are your dimensions? I would want ideally it to be 2 foot wide and 6 foot long (been basing it on being 6 foot long so far)
What about Rope Fish? They would work in there as a trio? One of the only fish around that tempt me to break my South American theme.
If you go for a GT just be prepared for the need to rehome them. The problem with cichlids is they dont stop growing and maturing until about 5 years old really and the first 3 years are really volatile as to how their personality changes - that goes for all cichlids really.
I think given what you have said this could be a really really nice tank
1 Jack Demspey (could probably do an EBJD here if you wanted)
1 Salvini
4 Firemouths
8 Silver Dollars (you could look at the patterned ones that are becoming available now, like the three stripe or the spotted ones.
1 RBTS
3 Rope Fish?
5 Hoplo Catfish
1 Common Pleco
When you put a group of Thoricthys together you will get a hierachy forming similar to Geophagus. Which often calms down other wise problematic fish.]
Where abouts are you from? Ellioti are getting quite common these days - most Maidenheads stock them quite regularly? Maybe I or an other member can point you in the right direction to find the rarer cichlids there are great suppliers hidden all over the UK these days
For me that sounds like such a good tank, loads of activity all over with the big school of Dollars and the Reed Fish and Hoplos will be between the top and bottom for air and swimming/rest then 4 incredibly colourful cichlids, cover a pretty broad spectrum of colours with the yellow/red/purple of the Salvini and the blues of the JD and the reds and greens of the Firemouths. And the interaction you will get from the cichlids is always good
Its why I keep them, its like having a tank full of small, scaley dogs
Wills