One thing I miss about the Infinity Engine games is the old AD&D Level Progression tables, you get a much more satisfying feeling earning 1000XP for a quest, instead of 100XP (a la 3rd edition, Star Wars, all other games using that d20 model).
i really liked the fighter's progression table
Level 2: 2,000
Level 3: 4,000
Level 4: 8,000
Level 5: 16,000
Level 6: 32,000
Level 7: 64,000
Level 8: 125,000
Level 9: 250,000
Level 10+: +250,000 XP
But yeah larger numbers feels more rewarding (and more of a monolith to obtain).
In conjunction quest/monster XP rewards should be high too, for instance, 2,000 XP for defeating a Flesh Golem encounter, instead of say 200.
YMMV.