I've played for a year or two. I use Wizard Mode to get by on things that nobody should survive. I've actually level-ported down to The Valley of the Dead. My favorite special levels in the entire game are Mine-Town, Fort Ludios, and The Castle. I mostly play as a human. I once wished for a monster taming scroll, read it next to a hostile dwarf, successfully netted it as a pet, and 'C'alled it Urist. He only lasted for about 20 turns, though, with only a dagger.
I sometimes wish for freakishly over-enchanted weapons and armor, like a +100 silver saber and a +75 cloak of magic resistance.
I like Mine-Town because I intentionally get the guards killed accidentally "accidentally", by waiting until a guard is a few squares behind a hostile monster, and I zap the monster, and therefore the guard, with my blessed wand of death (0:99).
I like Fort Ludios because of the amounts of soldiers (and their K- and C-rations), lots of boxes to use to hold loot, and the unsane amounts of gold. I've read the NetHack wiki article on the place and saw that it holds around 50,000 gold pieces. I wish for multiple blessed bags of holding, go and find all the gold, and put about 10k gold inside of each bag. I take the boxes and chests to hold all the other loot (like land-mines and bear-traps) to take to Mine-Town to sell for even more gold. Croesus can (literally) be a real pain sometimes. Fortunately, he wears no armor (bug?), and is quite vulnerable at range. I just shoot him.
I like The Castle because of the amount of soldiers as well and for the storerooms at the other end. They hold lots of valuable gems, good food, useful (and potentially magical) armor, and lethal (?) weapons. If I have any charges left, I simply clear out one half of the barracks with one shot for the loot they drop, move in, kill the soldier on the corner of the door, and zap the other soldiers. When it comes to the Dragons... I fight until I die. Then I refuse to do so, and I fight until I die again. And then... Well, you know.
Anyway, I never really play normally.
EDIT: I've also read the feat of DeathOnAStick in the wiki. His first attempt must have SUCKED, having drunk Rodney's CURSED potion of gain level after he dropped it. Bummer...