At the end of 5 tough games, I've come to a couple conclusions.
1) Air power is now paramount. Not only is anit-aircraft fire very important for keeping the rest of your army safe from flyers, but flyer-mounted firepower is much more useful than tank-mounted firepower. My Predators do a pretty good job against ground targets, but flyers get into optimal weapon range and fire arcs immediately and just blow them apart. The lower armor on flyers is a fair trade for their speed and ability to be only hit by snap shots with most weapons. On that note, the skyhammer missiles really aren't that impressive, even for their cheap cost. They've got a tough time damaging AV12, so I'll be looking to upgrade my Stormtalon to either the lascannon or typhoon.
2) My Scouts work just fine without Telion. The biggest advantage Telion brings is Stealth, but that is easily re-created by fortifying some ruins with the Techmarine or Lysander. His firepower isn't impressive enough to justify his points alone. He is, however, very worth it when paired with an emplaced weapon. He's the best option in Codex: Space Marines for operating one.
3) My army needs to be more mobile and aggressive. My games went best when I took the fight to the enemy, but my army didn't have the assault power or speed to really pull it off. A fast assault wing will distract the enemy from my firepower elements and allow them to do their jobs. In addition, a serious assault unit would be good defense against Flying Monstrous Creatures.
4) The Lysander led Sternguard worked out really well, putting our reliable firepower while Lysander presents a serious assault threat and absorbs wounds. What didn't work out was the Librarian. While teleporting the squad around was fun, it often led to them being isolated. I need to keep them near the other Sternguard squad and concentrate their fire.
When all combined, I think I need to add a Stormraven loaded with Assault Terminators. I can mostly pay for this by dropping the Librarian and Predators, so I'll be tweaking a new list.