I havent had a main bard in some years, so Im sure others may have better info. I dont know that there is any really good bard solo xp. I have kited with caster merc and tank/dps'd with healer merc in both ewk and katta kastrum deluge. You could try charm kiting but Ive never had much luck with that since they shortened the range on it. Current version is 75 (feet?) which is better than the 30 it was for some time, but still tough to manage.
Offer to PL 5 other people at the same time. Or molo with a cleric merc Charm kiting in... hmm, been a while, think last time I bothered was gorillas and crocs in Beasts Domain. Not aware of a swarm spot since. Bard melee/song damage output is very low compared to.. well, everyone. Unless you're swarming/charm kiting, then it will take some time to bring mobs down. REALLY try hard to get groups, have lfg up whilst swarming.
Charm kiting is the way to go. I've never had issues with the shortened range and I haven't tried it since the fade nerfs though. My last spot of choice were the wyverns in Shard's Landing. I never did find a good spot in CotF.
Something to note regarding the fade changes: the invis from fade now breaks charm (did not before). This means if you have a charmed mob and fade, the mob that was charmed will immediately aggro you.
