First of all.. AWESOME that you are actually looking into this; my wife simply tells me to order "whatever it is now"... I know most guys are PLENTY happy with that, but actually getting him what he wants without him knowing and getting ti right.. PRICELESS.
For a roof rack the obvious choices are either a Gobi or Baja rack. Those brands are the most popular (at least here on the forum), but in both cases there are some models to choose from so checking with one of his buddies will be the trick there.
Wheels are very taste dependent, but if he ever mentioned TRD's than Phil Stetson is your guy to check with (
[email protected]).
A suspension lift is a fairly big can of worms as well depending on the budget and what he's trying to accomplish. There is no short answer here, but Metal Tech has a group buy for UCA's at the moment and ICON is a popular supplier for full kits.
Bumpers/armor: usually people don't do these until after the suspension in order to handle the extra weight, but Shrockworks (Ask for Jim) and ARB are the most popular choices (personally I'll be getting a Shorckworks).
Sliders are something he can add now and again Shrockworks and BudBuilt are the popular choices.
Auxiliary lights are a great option to go with the rack and can range from Hella Micro 500 FF to Rigid Industries LED bars. Member Ducmonsta (Johnny) has a shop and if you send him a PM I'm sure he'll gladly help with any questions and or parts.
Hopefully this gave you some names to ask after and ideas of what you might want to get him.
Okki