Hash should last you about 3x as long as weed, but it usually isn't 3x as expensive if you know where to get it, which makes it a very economical smoke for those who have it available. Generally speaking, hash tends to be half-again as much as bud. I won't pay over $30 a gram for it, personally, which means I get high for half what I would spend on weed. That said, smoking hash alone isn't very fun. I have gone for extended periods with only hash, but it is always better to mix the two highs. As for hash smoking methods, there are are a few good options:
1. Top a bowl: Place broken up pieces or a flat "pancake" on top of a bowl of cannabis. The best way to do this is to flatten a piece that can completely cover the top of the bowl as thin as you can. When you hit it, keep the flame about and inch away from the hash and inhale slowly. The hash should bubble, but not light. Get the best results my trying to melt all the hash without torching it. Once it is completely melted into the bud it can be hit nomally. I've seen people pre-melt it into the bud with a lighter before hitting it, but I think you get the best tasting hits while the hash is still bubbling.
2. Mix it in: This can be done buy breaking up pieces to mix in with a bowl or joint, or by rolling a "worm" and "burying the worm" in a joint. The worm in the joint is very, very nice.
3. Hash pipe: The common metal pipes with screw on tops are probably the most convenient hash device around. With a screen in it, wads of hash can be packed and the cap screwed on. Just hit it thought the hole in the top. I've carried one of these with hash in it for a whole weekend before, taking hits whenever I got the chance. Small glass pipes are also good, as long as the hole in the bottom of the bowl is small enough. Screens are also a good option for these, as hash likes to melt and flow into the chamber on glass pipes, but may not be necessary depending on the pipe and the hash. In general, your favorite glass piece is probably best for the varieties of hash that don't melt as much.
4. Hot knives: I have a pair of glass hot knives, but have done it many times with normal butter knives. With the glass ones, you need to heat both knives or you risk breaking them from the shock of placing hot glass against cold glass. With butter knives you only need to heat the tip of one knife. This is best done on a gas stove, but I've done it with a bic lighter before. Stick a bead of hash to the end of the cold knife, then press the tip of the hot knife against it. It will melt and smoke will rise of the tips of the knives as you squeeze them together. Inhale the vapor just above the tips of the knives. Careful not to burn your lips!