First, I went with XFCE. I don't hate Ubuntu proper but Dash isn't as efficient as I'd liked so I decided to step back a little.
Second, I installed a whole slew of software: The heroku toolbelt, build-essential, playonlinx, chromium, an xmodmap script, libreoffice, steam, dropbox, calibre, gnucash, audacity, gvim, vlc and many more.
I also got rid of some apps I'm unlikely to use like gnumeric, abiword, and thunderbird.
With that out of the way, here are some of the tweaks I've used:
1. On upgrade to 14.04 your trackpad may not work as it did before. You'll want to try blacklisting ic2_hid as mentioned in this post.
2. Trackpad still not where you want it? Try installing gpointing-device-settings as described in this post.
3. Want to rest your thumb on the trackpad the way you did on Mac OS X? Me too! I haven't been able to figure it out yet though I did find a blog comment where somebody left some instructions for debian. Didn't work for me but if it works for you, drop me a line!
And that's where I've gotten so far. Most of the other tweaks have been personal preferences to get the right programs and key bindings.
So what's next? I'd like to figure out that Operating System not found error (boot-repair did not work for me). I'd also like to try running a game like Hearthstone or Wildstar via PlayOnLinux. And then if things go really well, maybe try to get a VM set up with Windows or MacOS.
PS: if you mess something up badly and need your service tag number to get support from Dell, you can find it by typing. Probably do that now. :)
$ dmidecode | grep "Serial Number"