If you want clowns or royals (or any of the panaque family, even some hypostomus - like rusties) you have to have bogwood as it forms the main part of their diet. But personally I'd say with any plec you should have some about - as they rasp on it for the fibre.
If this will be your first plec, I wouldn't go for the gold nugget unless you can get a larger specimen from a private home, rather than from the LFS. They're notoriously hard to acclimatise after being shipped, and many of us who've got youngsters have lost them within weeks of getting them from the LFS. Basically when they're in transit for a long time, their gut flora dies off, and while their body desperately tries to replace it in their new home, they can die of what is effectively starvation. Same can be said for some other plecs too (including royals, although not to the extent of the GN). So if you're getting one of the more sensitive plecs from the LFS - always check it's got a nice tummy on it - not concave, no sunken eyes (although by the time they've got these death is pretty inevitable apparently), and that they've had it in the shop for a couple of weeks - and have got it eating well.
Also one other thing to remember is that if you're wanting panaques, they cant have a high level of protein as it can kill them - so if you want to add other plecs that are omnivores or prefer more meat, they wont be compatible. Some folks get away with it, but it can cause real problems long term, according to those in the know.
Hope that's of some help - good luck deciding, there's so many beautiful plecs out there, it's great to see someone else interested in them - and with a decent sized tank to provide for some of the bigger fellas!
