After having played through two lives as a PDK bard, once pure and once with the requisite 2/2 fighter/rogue lives, I have the following ideas;
1: Heal and Wail should be 6th level spells, not a capstone. This will still require at the very minimum 16 levels of bard, but realistically, more like 18 to get enough spell slots to take even one of them. This allows a small degree of flexibility with multiclassing a bard without missing out on a real heal spell. Wail isn't going to work in EE anyway, so that's going to be a flavor/convenience thing on some builds only.
2: The capstone should include Inspire Excellence. Or possibly Inspire Excellence at 18 and Lasting Inspiration at 20. Either way, these feats really should be auto granted. The bard only gets 7 feats in heroic levels, and not allowing bards to take either a casting or melee feat in Epics is not fair. Especially since every other song feat is *auto granted*. This would allow the bard to pick up another heroic feat they didn't have room for, or some other epic feat for melee or casting if they desire to try to be somewhat competent in that area. Consider that of those 7 feats, it takes 4 melee feats (PA, cleave, great cleave, imp critical) as well as an investment in strength to get those feats (even for cha based melee bards) or 3 caster feats to qualify for epic spell focus so that you can actually enchant something once in a while at epic levels. (4 if you want any spell pen) Quicken and empower healing are pretty much must haves no matter what, as otherwise you won't even be able to heal yourself let alone anyone else.
As you can see, this doesn't leave a lot of feat slots open for anything else. For example, Force of Personality. Or completionist. Or any meaningful spell pen. This pretty much requires Warchanter/melee based bards to multiclass fighter levels for the feats only. Casters are SOL.
3: Scale the songs for epic levels. I won't mention fixing the broken songs as we all already know about and agree on that. But the songs need to scale for epic levels. Inspire Courage is +4. Whoopee. I have an item that gives me +8 and it has another useful ability and an empty augment slot. "For Cormyr" a PDK racial ability, has the potential to give +20 or more to the entire party. While it is of much shorter duration and more difficult to implement, it is at least worth making the effort as that's a noticeable increase. Arcane Might doesn't stack with ship buffs, making it essentially worthless. Sustaining song needs to scale with levels. Ticking off 2pts of healing (5 if you have a tone of heal amp) when the monsters are hitting you for 450+ is barely noticeable. The only time it's even remotely handy is doing explorers as it has plenty of time in between altercations to keep you topped up. Spellsong vigor, same thing. Although I understand why you would not want to change this as it is quite possibly the only song that is even occasionally asked for by party members. (And even then, not that often as most casters in EE have 3000+sp, cheap slas they can spam, and their own methods of regenerating sp)
4: Speed anything to do with CC up. I have quicken on my disco balls, but the mobs AI is currently set on "run past the caster at light speed as soon as you become aware) so most of my disco balls end up where the mobs used to be. If it's quickened, why does it still take 3-4 seconds to cast? All of the cc based songs should be almost instantaneous. It is highly embarrassing to run into a room full of mobs, start singing enthrall, and die before you finish. Yes, I know you have to start singing first, and time it so you run in at the end of the song. But then you miss the mobs in the back half of the room and they kill you while you're on cooldown. Or your timing is off just a millisecond (lag anyone?) and the song doesn't hit at all. Any and all combat related songs should be much, much faster. Disco ball needs to cast more quickly. Why there's any cool down on any song, I have no idea. You should be able to sing songs one after the other, rapid fire.
What I have tried to do with the PDK bard builds is to create a bard that is a true swiss army knife... melee that's not embarrassing, and some spell casting that works. This toon has all the past lives for the spell pen, so Otto's is useful. No saves, dc doesn't matter. Although it's one target and it's mostly a convenience thing to keep mobs from running back and forth like crack addled kobolds so I can hit them properly. Disco ball is close... with a little boost in dcs it might be helpful. The songs, of course, work great... just not in 99% of the parties out there as they're easily broken and with all the manyshot/furyshot archers and massive aoe spamming casters, most times they just plain don't work at all. So the investment in the songs is where the whole things suffers, and the bard becomes less and less... a bard.
Now you're saying "all this stuff is too much!" And I'm saying too much is really still not enough as the bard has been left behind for a very long time. But I think this is a fair start to bringing the bard up to par. And it allows a lot of flexibility in play styles; you can be the ultimate support toon, you can be a melee's best friend by watching his back, keeping him hasted and healed, and you can even CC almost as good as the wizards that have no specialization in enchantment.