A few recommendations:
Eat at this place in shibuya
at least once:
http://r.gnavi.co.jp/fl/en/g371701/
Their food is next level. Chicken bread (amazing!! bread with a kinda chicken paste on it! am must eat!!)! Deep fried, fried rice dumplings!!! Cheesy crispy, springy roll type things with kimchi!!! They also have a really nice floor seated balcony type area.
Print out and use this coupon for extra drinking benefits and discount:
http://r.gnavi.co.jp/fl/en/g371701/coupon.htm
(there's also a menu tab on that site but it doesnt include everything)
Alcohol wise, drink Shochu, not sake. Best drunk on the rocks for the best flavour, plus drinking it without ice is asking for a hangover. It's distilled in a variety of flavours, the best of which are sweet potato (
imo, one of the most common), buckwheat (
soba) and
shiso (a kind of herb, looks like a nettle and is often served with
sashimi (raw fish slices).
You also need to get loads of ramen down you. I'm not the expert so i'll let reverendmedia fill you in on that but you definitely need to eat tonkotsu flavour (pork broth). There's a chain called jangara ramen which is pretty good.
One place i always tell people to go (and always have satisfied customers) is 109 in Shibuya. It's one of the really tall buildings you can see from the train station exit and has a big '109' plastered at the top, can't miss it. There's nothing you'll want to buy from there and you don't have to spend any money, but i can virtually guarantee satisfaction. Remember. 109! 109! 109! 109! 109!
You should definitely go to Harajuku on sundays, that's the day when all the crazys come out. Just outside the station you'll find all the lolita goths, cosplayers and 'musicians' (they make noises at any rate), it's basically a showcase spot for the alternative, weird and wonderful. Walk on a bit further and you'll come to the entrance of Yoyogi park, outside there should be all the 1950's peeps with their sideburns, leather jackets, jive dancing and motorbikes, they're class. Then inside Yoyogi park there's insane amounts of things goin on. Loads of sports, dancing, drumming, people practicing their arts such as opera, tap dancing and brass orchestras. Also just across the bridge in the park, on sundays they sometimes have flea markets, cultural festivals and stuff so worth checkin out. Then runnin alongside the park there're loads of people performing music but they also put up soundsystems, came across a sick reggae one before.
Oh, and you're going in cherry blossom season so you'll wanna spend as much time in parks as you can, best to go with people if you know anyone out there, bring food and booze and have a day sitting under the trees.
In terms of where you stay, being central-ish is good because once the trains stop running (around 12:20 usually but it depends where you need to get to) you're stuck. It's no biggie though coz if you're out on the town you can just go and get a karaoke booth with all-you-can-drink till the morning for about 15-20 quid. good times. if you're not on a singing/drinking one you can always go to a net cafe. nothing like net cafes in the uk, they're private booths, with huge reclining leather chairs, sofas, ps2's (maybe ps3's now), unlimited refill drink machines, mangas, etc. they're also pretty cheap per hour so you can sleep there for less than a capsule hotel if need be. it's worth going to one at least once even if you don't need to.
will post any other ideas i have.