My #1 recommendation on desktop twitter clients is.....NONE.
Seriously, don't use one, ever.
It's the most insanely massive pointless timesuck in the history of procrastination and timewasters. Imagine if you had a permanent desktop application that featured Google Reader scrolling up every new post on every blog you follow combined with every new link on delicious from people you trust and every photo added to flickr by your friends plus tons of instant messages sent to all, constantly streaming with no end in sight.
IT'S A TIMEWASTING FIRE HOSE OF INFORMATION.
Do what I do, which is every few hours if you're at a stopping point or bored or whatever, go to twitter.com in a browser. Scan through the missives from your friends, maybe page back a couple pages to catch up to the last time you checked. If you think of something you need to say, toss it up as a new message.
THEN CLOSE THE BROWSER TAB AND GET ON WITH YOUR LIFE AND WORK.
I speak from experience. I've tried half a dozen twitter clients but if you make a habit of coding, photoshoping, and/or/especially writing for a living it gets in the way much more than it serves as a creative reading or writing outlet.
It's like leaving a TV on in the same room while trying to write a novel. Just don't do it.