I must confess that when I determine treasure, I just take the
total value as a proxy for the value of items possessed by a person or creature. So if the valmpire lord was supposed to have say 5000gp of goods (on his person and in his lair), I might say things like ermine robe (value 250gp), gold-plaque belt (value 300gp), 3 assorted rings (non-magical, total value 1600gp), statuette of silver nymph (350gp), three rich tapestries of scenes of battle (total 1500 gp), etc. etc.
In other words, I often hand out far
less actual cash than the game determines. It makes for greater verisimilitude
and importantly gives something for the party's social characters to do - making a good sale of these commodoties is a staple job for them.
As for the D&D economy itself, frankly the numbers are screwed up wildly. However, you must ask yourself whether it really is worth reworking everything for only a small gain in gaming detail. I've played around trying to get numbers that make more 'sense', but then I have to think 'make sense' relative to what? Europe 1300AD? Or Imperial Rome? Or Renaissance Italy? Or Mughal India? It's impossible to draw up absolute standards, and as a typical D&D game incorporates so many different elements, it seems abitrary anyway!
One final thought: I am quite happy to consider the higher level PCs as the gentlemen-adventurers and playboys of their world. As such they will often lead luxurious lives when they're not 'in the field', and they'll probably spend far over the odds just for convenience's sake. I've had a party of a mere two adventurers spend over 100gp for a single night in an inn, with all entertainment, food and drinks thrown in. They were celebrating their successes and their survival, and just wanted to kick back, buying the very best of everything. And guess what? There are people always willing to accept large sums of money as proof of their 'sophistication', and provide them with a good time!
