Grinding spells is silly but necessary. I was sick of how slow things were leveling so I made some gear that made alteration spells cost 0 magic, sat in solitude and cast "Detect Life" on both hands for about 20 minutes while I played Scrabble on my phone. I did a similar thing with some poor fox in the wilderness, alternating between Calm and Courage spells to slowly level Illusion.
The worst part about how slowly the spells level is that they don't get any stronger as you get more powerful (unlike warrior skills), so although the destruction mage is hugely overpowered early, it's almost a joke later in the game. The Master level destruction spells have a cast time of several seconds, use 800 or so magic without "fortify" enchantments to reduce cost, and do so little damage that you need to hit higher level draugr with them 10-15 times to get a kill. What the hell? It's really disappointing to invest so much time into leveling destruction to get awesome spells only to have them be more worthless than the spells you start the game with. I guess there are some mods that fix this by making spells level as you progress, reduce the cast time of the Master level spells, and all that, but I haven't checked them out.
Speaking of mods, there are two more that I have to mention.
Skyrim Realistic Overhaul is a texture mod that replaces a lot of the landscape textures. I like it more than a lot of other HD packs because it tries to keep the same look as Vanilla, albeit with much crisper and more realistic textures (almost photorealistic in some cases). It looks great ingame.
Realistic Water Textures and Terrain is one I've mentioned in this thread before, but the author just updated it with new waterfalls which look awesome, as seen below.