Well, I think monk is the weakest class in core, but I also like martial arts and asian-themed stuff in general, so I like the class anyway. I'll provide a baseline for Dandu to compare a Bard 20 to. I'll assume PH/DMG/MM only, 32 point buy and no multiclassing? If MCing is ok, it REALLY would benefit a core monk to dip a caster class for wand and scroll access. Oh, and no using the Leadership feat, ok?

Not doing magic items yet, that's always the biggest pain to figure out for high levels. As an elf, he definitely takes advantage of the longbow proficiency to have a respectable ranged option, and can fight unarmed easily without needing to drop the bow.
Wood Elf Monk 20
Starting: Str 16, Dex 16, Con 12, Int 10, Wis 16, Cha 8
At 20 (before magic items): Str 20, Dex 16, Con 13, Int 10, Wis 16, Cha 8
Feats:
1 Improved Grapple
3 Power Attack
6
Improved Natural Attack (Unarmed Strike)
9 Weapon Focus (Unarmed Strike)
12 Improved Critical (Unarmed Strike)
15 Improved Initiative
18 Cleave
Monk bonus feats: Stunning Fist, Deflect Arrows (with no reach weapon or splat book feats, I don't think Combat Reflexes means much, swap if you disagree), Improved Trip
Skill ranks:
Balance 5
Jump 5
Listen 23
Sense Motive 12
Spot 23
Tumble 12
Tactics: Shoot the bow and run around really fast to harass enemies; flurry of misses and/or ground and pound when in melee and doing so isn't suicidal. Beg the DM to let you throw away Perfect Self for no return benefit at all since losing Enlarge Person is a greater penalty than anything some crappy monk capstone ability could ever hope to be.