A colleague of mine has both these sets sealed in box. Some storage wear. These sets are cool with the flap design. 
A check on BL shows not many for sales and not much price history info available. 
5976 is the River Expedition. 
5986 is the Amazon Ancient Ruins. 
5986 new price is nuts!

What would be a decent list price if to sell
 

With such old and rare sets, I think Bricklink isn't the right platform to sell them on. 

These are best sold through auction, on either eBay or Catawiki, I suppose.

I would not go for an auction. These are low volume sets and you could get burned easily. I would post them with a high fixed price and be patient. Maybe accept offers. Depending on where you live, I would try a local sale. You save fees, shipping, and tax and you don't have to worry about getting defrauded like I would with a high value ebay sale.