In my greyhawk campaign, since dwarves and elves are not playable races (gnomes and halfelves are), I use Ulaa for dwarves and gnomes, and Ehlonna for Elves. Works out well imho and simplifies the pantheon a bit.
Most orcs would worship (and follow) Iuz though. Halflings would revere Beory (Also not playable race)
The players revere Fharlang, Heironeous (The pally in the group), one is a warlock of Bel and one a Nature priest of Beory. The gnome wizard did not state his belief so far, he would either pray to Ulaa or eventually to Boccob.
I think I could not do similar things in FR eventually, you could replace Ehlonna with the goddess that Drizzt reveres, Milekki or so, but you got no Mountain god like Ulaa wit hties t odwarves and gnomes there (Maybe there is one but I am not aware of this)
My experience is that PC do worry about their own god if they do at all. So a Pantheon with 35 gods is nice fluff but a load of baggage also.