All the dive operators I know of do a two tank  morning trip, followed by a
separate two tanker in the afternoon. Usually a deep (100ft) wreck followed
by a shallow reef dive. There are numerous dive operators to choose from.
I've personally dove with Ocean Concepts and Dive Oahu. Ocean Concepts
http://www.oceanconcepts.com/index.php/content/view/full/2  is running from
Waianae (45 min to hour drive west of Waikiki) diving on the Mahi (collapsed
mine sweeper) followed by a reef dive. Dive Oahu http://www.diveoahu.com/ 
is much closer to downtown. They usually dive the YO-257 followed by a
shallower reef dive. My preference is for Dive Oahu as the YO-257 is a
really nice wreck. Normally crowded with sea turtles and boocoo fish. I
haven't dove the Mahi post collapse, so I can't really describe the diving
conditions there. It used to be really good, just a long drive with loads of
traffic to contend with. This one is best done mid week as the traffic won't
be as bad. North shore I tended to avoid as the diving conditions aren't the
greatest. The water is usually more silty and coral growth not as good as
the south or west sides of the island.
Have Fun!
Aloha

If U can find an operator who's going to the Corsair (off Coco Head) that
can be a cool dive.  About 90' with a stiff current and vis that makes
Hawaii legendary.  I accidentally took my first good pictures there.
Followed by the Shark Cave (?) makes a nice 1/2 day of diving.  Seas can get
pretty dicey on the S shore this time of year, though, but U might get
lucky.  Dove there the first time with a tourist op called Taking the Plunge
(moooooo) and after that hooked up with Capt Bruce, who used to have a DM
named Fritz who dove with a Bend-o-Matic.  You might have trouble finding an
op 2 do 3 dives on one trip.

I have used Island Divers the last 3 times I have been to Oahu.  They will
pick you up at your hotel.  I enjoyed the YO-257 and San Pedro wreck dives.
The corsair is nice to see, but kind of boring. $89 for 2 tank dive, if you
bring your own equip.

http://www.oahuscubadiving.com/index.php?

Dave

I have used Island Divers many times while in Oahu.  I would do the
YO-257/San pedro wrecks or the Corsair.

They will pick you up at your hotel too.

Dave