Welcome Craig!
You should have a look at a thread I posted a few days ago, "the best 5mm under $200. It's a pretty informative read. I too am in your shoes looking for a good planetary ep. I wasn't happy with my 10mm that came with my dob purchase- just wasn't cutting it with the planets.
Get the barlow, but get to know your eye pieces first. A good start up would be 10, 15, 25 and a 30ish. Do the math on the barlow magnification to make sure you don't double up on ep's. My 25mm is the most used and favourite. A 30mm ultra wide angle is fantastic for sweeping the sky with to find things; then when you find something, you can up the power to observe. Don’t give up on your bino’s- they’ll still be your best friend and come in very handy with your telescope. Nothing beats the simplicity and ease of just getting out there with the binos instead of drag scope and equipment out. Very relaxing and no cleaning up. Here is a link for bino targets – have a go with your dob as well. The Beehive cluster just above Mars looks amazing at the moment!
http://www.lightandmatter.com/binosky/binosky.html
.What you’re after is a planetary eye piece. A 45deeg fov Ortho’s) one would not be so good for a dob as it would be too hard to manually track. Good eyepieces can tend to be a bit expensive as you will see in my thread. If you want the best view on the planet (contrast & detail) don't barlow it. Barlow it if you just want it more magnified and you don't care if you lose a bit of quality. The more glass you add (barlows and wide angles, the more light you lose = less detail).
Your eyes will adjust to taking in detail in no time. Your eyes need to learn to see the detail in these objects. Dark adapt your eyes first (20mts). I’ve only been doing this for 4 months, and now I can spot star clusters and nebulas with my naked eye! Also, learn the art of averted vision, if you haven’t done so already- images will pop up with more contrast.
Astronomy 2010 book is an invaluable guide- Andrews communication’s online are selling it for $20 incl. postage (normally $30). A planishpere is very handy, and so is computer software programmes such as Starry Skies and Stellarium (this one is free). You will also need lots of Aeroguard, a red light torch, a stool to sit on,
alcohol (keeps us warm and gives good company, it does, it just does!– gets awfully lonely out there you know), )and a partner that doesn’t care that you find the sky more interesting than her!
My hubby's just glad to shut me up and chuck me out there so he only has to deal with 500 words out of my mouth that night.
The people in this forum are a great bunch, and there is never a silly question to ask, we all had to start by learning. We enjoy helping others who are as fascinated with this stuff as we are.
Happy telescoping!
