Regarding keep/destroying the Collector base..
It's all perception, to be honest - keeping it would give you a much needed edge over the Reapers, should it's information turn up anything incredibly valuable - but who knows?
It reminds me of the choice to keep the wife's body on Shamesh or whatever his name is - supposedly there'd be some advancements in shielding technology against the Geth - but if you turn them towards your side during Legion's loyalty mission.. is it needed anymore? Not likely.
Who knows what will turn up from your decision? I destroyed it - not because I hated TIM and Cerberus, hell - I love them, but because I perceived the whole thing to be an abomination. To be one of those things that would constantly remind my Shepard of his failings at not being able to protect humanity.
People died on that mission to destroy that base - to not do such after them giving up everything would be to spit on their name, in my opinion.
TO EACH THEIR OWN!
@shinobi - You can't force good writing. It's something you need to take your time with and write as you go. When you get those sparks - let your imagination run loose. One of the things I did when I was working on my story with Meg was to just write a scene.. maybe related/maybe not related to the story in general, but to just write a scene that came to my head. Most of those scenes ended up in our final story.
For example, the fight with the mech? I had an excerpt written about fighting a mech when I was initially writing the story - and voila! It turned into being the conclusion to the fight with Toombs.
Let your imagination free - and who knows what you'll end up writing.