I just finished my drawn-out extended replay of Mass Effect. The last autosave before the Saren battle was 39 hours. I still only made to it to level 56, I have no idea how you're supposed to get to 60. I did everything and hopped out of the Mako for every battle (save for the first couple) for the extra XP. The only assignment I didn't complete was the one where the Salarian wanted you to help cheat on the Flux gambling machines.
I remember liking the game much more the first time I played it. But by doing all the side missions, it really pounds home just how lifeless the game can be, how desolate the game universe is. Go to this moon/planet/asteroid, go through these pre-fabed bases/mines, wash, rinse, repeat. No matter where you go, there's like a max of 4 living people in any one place. Even the Citadel, which is the "center of galactic civilization," is less populated than a neighborhood grocery store.