Hike Diamond Head. Check out the Dole Plantation. There was a pretty cool little music store in Honolulu last I was there, "Island Guitars" maybe?
We went to a flea market that had a booth full of all different level and brands of Ukuleles. I kick myself for not buying one, as they were well-priced.
Those would be on the list I am posting later but I don't believe his mother will want to hike Diamond Head. Dole is a great place for them and it isn't very far from where they are staying.
However I can list all the guitar shops that I go too when I am there.
Guitar Magic/Hot Licks (Waimalu) - Say hi to Tom Hinson or Carlos that I sent ya. The owner is Zack Peterson.
*Majority of instruments are Fenders with some Gibsons, as well as some other brands - ie: Ibanez, ESP, etc. - some used but more new. Gear is beginner to medium with some top end stuff. This shop is a great accessory shop filled with spare guitar parts, pedals and other guitar items.
Island Guitar (Ward Warehouse on the 2nd floor) I know that Peter used to work there, uncertain now. Don't this shop very much.
*I don't visit here much as the Ward Warehouse is a major tourist spot. Mostly medium to high end gear but still friendly for the beginner or novice. They do have a great selection of Taylor Guitars and Gibson guitars. From what I recall, the carry Boogie Amps too.
Coconut Grove Music (Kailua) - Say hi to Frank, Rick and Mark (Owner)
* This is a friendly store with beginner to medium gear. The guys are great here and run the open mic jam at the end of the month in Kailua. I have gone to two of the jams and just had a great ole time. You'll find Fender's and Danelectro's in here plus ukes and acoustics as well.
Dan's Guitars (Moilili) - My friend Dan owns the store
*This is my second favorite shop. Mostly medium to high end gear but still friendly for the beginner or novice. They have a great assortment of ukulele's and acoustic guitars. For electrics LSL, Ernie Ball and other higher end instruments as well as some medium and beginner stuff. What I love is finding used gear here. I got my Danelectro and my Gibson Melody Maker used here. They also have a great selection of boutique pedals as well as the unusual stuff such as Wampler, Fuchs and Mooer.
Good Guys (Kapahulu) - Clay and Bryan own the store. Say hi to the Owners, Vernon & Dennis.
* This is my #1 shop. Really a local favorite as well and when mean favorite....a local for more of the discerning players who work in Hawaii. The store carries alot of used instruments (which I love) as well some new items. New items might be custom made by Bryan as well some oddities too. The shop is small and tight so walking room is limited but talk about stock piling gear into a small shop.
I have been told that there is another shop in Wahiawa but have never gone there. There are a few other music stores such as Harry's Music (Kaimuki) - not much stuff and Easy Music (Moilili and Pearl City) - Kind of the GC/Sam Ash of Hawaii that I don't care to go too unless I am absolutely bored or looking for some oddity I need for a jam.