Dragonlance Vs Forgotten Realms?
Unless you're REALLY familiar with one or the other setting, don't use either. Either use a 3rd party setting or use what you like from each one (and other sources) to form your own homebrew. It will take a little work, but it will be worth it because:
you avoid the player familiarity problem (players know more about the setting than you)
your word is truly final
you can use the best of whats out there and houserule the rest
you can avoid things you feel are truly broken or problematic, like certain spells or PrCls
and so forth.
In a homebrew, your house rules have more weight. For instance, I never use generalist wizards anymore- specialist mages only in my campaigns, and I let Paladins and Monks multiclass freely with each other and with Clerics, assuming no alignment conflicts exist.
Something else that may help you out: after you decide on how to generate PC stats and what classes and races can be used, insist on a 1-2 pg background (double spaced- no need for a novel) on each potential PC. By forcing the players to think, they'll help you shape your campaign.
In fact, their backgrounds may even suggest adventure hooks, and it will give you some insight into what kind of campaign the players want...hack & slash, amateur theater, a mix of both...
If a background is particularly good, reward the player with some bonus XP or a special item (no more than 2000gp value) or contact for his PC...something that goes with the background. The fighter gets his family's ancestral sword, the mage gets a powerful mentor (good for answering questions), the rogue has a pal who is a fence or who has a safe-house, etc.