I'd like to see Fimbulwinter from frostburn in there. By itself it's not that good, but with a little bit of boosting it become insane.
Empowered Extended Maximized Fimbulwinter. That's 7056 feet of snow by the end of it, with the snow piling up at 7 feet per day over 1008 day. Who doesn't want to drop 1.33 miles of snow on something?
(you can only get the full effect vs. hot climate areas if you cast during winter, fall or autumn, but the snowfall should stay at full the whole 1008 days.)
And those three meta-magics I want to apply all have an incredibly easy way to put them on a spell sans meta-magic cost.
As awesome as it sounds to drop over a mile deep of snow over an exceptionally large area, it takes
three freakin' years for the spell to do that. What's more, there's technically no benefit to dumping more than 5' of snow on an area. A 20' tall giant, RAW, can just as easily walk through a mile deep snow drift as he can a 5' deep snowfield.
Moonweb from Player's Guide to Faerun is a pretty wicked spell. Create a wall that you can shoot (or cast) through, but your enemies can't? Yes please!
The shield is circular and only 10' high, so it's not unthinkable that something can just fly over it to shoot you. The wall is only one 10' square, so it's only useful in narrow passages, but enemies on the other side can, in that case, just run away. If you go through the shield to chase them, then they can pin you up against your own spell effect.
Wall of Force, on the other hand, is a lot more versatile. You can't shoot through it, but you can trap creatures inside it and make a deathtrap around them using a spell like Scalding Mud.