Personally I only give XP for "Treasure recovered from the dungeon or wilderness and treasure granted as a bounty or reward" on a 1GP to 1XP basis. I don't give XP for magic items, or overcoming monsters.
If find this keeps my games more focused on finding gold, rather then fighting, though of course the players always quickly find their own goals in the world ... and sometimes that's hunting down monsters.
I am fairly generous with treasure placement, and one needs to be - remember that for a party of six to advance to level 2 they need to recover approximately 12,000 GP (Likely more). To level 3 it's another 12K, Level 4 it's 24k an level 5 it's 48K... so getting a party to level 5 assumes no deaths and around 100K in GP recovered! The question is how long do you as a table want that to take? It becomes especially tricky if you are using cn based encumbrance and coin hordes because I character can usually only manage to carry out about 1000cn in weight per dungeon crawl. If they are carrying silver that's 100 XP... So really treasure logistics and finding gems and jewelry matter a lot.
I've running XP for spent GP before - and it's good, but it does require a more active world and things like training costs or allowing the players to bank gold for larger projects (like strongholds) that still give XP.