My party is currently at 23rd level, all the way from 1st.
My recommendation? Steer clear of Bastion of Broken Souls, for one. It's very sloppy, in my opinion. It goes out of it's way to nerf a good deal of the player's abilities (particularly divination powers), is very linear and features some elements that just don't work very well. The very first encounter throws a cool but vicious creature, the Cathezar, at the party, and then sends in a epic-level (but pre-ELH) NPC to save the party. You chase her down, go through a series of throughly unnecessary combats (such as fighting a pair of celestials who are only doing their job containing an ancient god...and then you fight the god and his minions, who aren't evil). Ultimately you find your way to a series of uninspired slugfests in the positive energy plane, to fight the BBEG, without much preamble or semblance of a story.
Storm Lord's Keep is another module that was released in conjunction with the ELH, and it's a dungeon-crawl that is generally uninteresting and sometimes silly. Things like making all the walls of the castle regenrating force-walls, to prevent players from destroying them, epic-level monsters that are just sitting around waiting for the PCs, and other things that are designed to prevent the players from using their abilities to get around the author's limited set-up.
In short, both of these modules make the mistake of creating a very uninspired dungeon-crawl, and then coming up with ways to block the players from bypassing it. They don't seem to understand the full ramifications of the player's abilities.
The single best high-level module I know of is "Lich Queen's Beloved" from Dungeon #100, I think. It's a 3.5 module, it's well-written and easy to mold into your game...and the author gave serious consideration of ways to allow the PCs to flex their muscles without derailing the adventure. If you get the web-enhancement from Paizo with the details of the surrounding city on the body of the dead god, you can extend the adventure further.
Generally, I would use some resources from other locations, and then adapt them to your own game. Lord of the Iron Fortress is a better module than Bastion, and could be upscaled fairly easily to work at a higher level (some extra levels here and there; buff up or replace some creatures, etc.). Swap out the mind-flayers with the advanced mind-flayer from the 3.5 MM, for example, or add a few more class levels to them, and add another shield guardian into the mix.
