there are sooo many different fish.... you are going to have to narrow it down a bit and say what fish you like and we can say if they will fit or not.
do you want a comunity? agressive? reef?
you literaly have hundreds of options.
i personaly like the small wrasses and gobies. and clownfish are always a good thing to have.
as far as a cucumber, that owuld depend on the species.
When you say clownfish it is too broad. you can have Maroons which are highly aggressive or skunks which are more placid. cucumbers are really all that great, i got a black knobby cucumber on some LR and yes it is good for maintance but not all that great to watch.