A question for you kids who are big on Doom... are there any Doom bands with great vocals and great lead guitar play?
If you're talking "traditional" doom bands, my #1 recommendation would be Ozzy-era Sabbath. Most of the bands mentioned in this thread -- the Pagan Altars, Pentagrams, Count Ravens, and Saint Vituses of the world -- are based primarily on this sound, but are not quite as good. Certainly none of them can touch the greatness that is Iommi, and the sound is an acquired taste.
However, branching out into different kinds of doom, particularly the more thrashy or proggy types, will probably yield different results. Bands like Candlemass, Solitude Aeturnus, Memory Garden, Veni Domine, and their like are much more interesting IMO, vocally and instrumentally, than most traditional doom. I'd even lump old Tad Morose (Andren-era) into this group, but just barely.
There's also doom-death (ie, Saturnus, Daylight Dies, Lacrimas Profundere, etc.), but I find that genre to be excruciatingly boring. Still, it's one of the genres in metal which seems to be growing the quickest in popularity. A few examples in this group that I personally enjoy are old November's Doom, old Katatonia, and Moonspell (their earliest and latest albums, but not that boring-ass mid-period shit by them).