How much is that in gallons? You should be able to find an appropriate volume calculator if you search on google.com
Clown loaches like to be in groups and grow quite large. They are intolerant of salt (just something to consider as this is often used to 'medicate' tanks) and are highly susceptible to ich. Unless your tank is a good 60 gallons - and more is better - forget these.
The plecs you mentioned are both lovely but keep in mind that most are territorial and need room for themselves. Also, they cannot simply be treated as scavengers or algae eaters and need to be fed appropriately. Some species laelled as gold nuggets grow large - make shure you know how large and identify it correcty so that you know your tank will be large enough.
Pictus catfish are lovely but can eat small fish when full grown and are largely nocturnal but active. They can sometimes harass slow-moving fish like gouramies, however.
Considering these other fish you're considering, I'd reccomed one of the larger gourami species such as the moonlight. These do well in trios (1 male, 2 females) and grow to 7".
If the tanks is around 60 gallons, kissing gouramies might make an even better choice. These grow large though so don't overcrowd. They cannot be sexed visualy. I'd go for a group of 3 and replace individuals if necessary (ie swap some round if you get aggression between two particular fish). Keep in mind that 10"+ isn't unusual. One big plus with kissers is that they lack the leongated ventrals of other gouramies that make irrisistable nipping targets for many tankmates.
Thick-lipped and banded gouramies are peaceful gouramies that grow to 3.5" and 4" respectively. These are also options kept as trios or in small groups of a few males and twice as many females. Don't add these if any of your other fish will be aggressive and try to ensure the tank contains at least some tall and floating plants.
The other species to consider is the three-spot gourami. Large groups of females are relatively peaceful. Avoid males and don't try to keep a small number as they are very likely to turn aggressive. Males have a longer and more pointed dorsal fin. This fish grows to about 6" and there are several color morphs including gold, blue, opaline, cosby, platinum and lavender.
Have you considered any of the ctenopoma species? These fish are related to gouramies. They tend to be shy and relatively peaceful though they are territorial and will prey on smaller fish readily. In a planted tank with lots of hiding places they make wonderful mid to bottom-dwelling inhabitants. One of the most popular species is Ctenopoma acutirostre. These are also known as leopard bushfish or spotted climbing perches. There's a profile in this forum's fish index (and there should be one for at least some of the other fish I've mentioned).
Again, a lot depends on tank size though and on what you end up wanting to keep.
