I have owned many Harleys throughout the years and I currently have a 2006 Softail and a 2008 Ultra. In most respects, the bikes are improved a little every year. The new frame is stiffer than the prior frame and handling is marginally improved. I have done a week and 1800 miles on a 2010 this year and found the ride nearly identical to my 08. There is nothing wrong with the 08 and down frames. You never hear of one failing and I personally have never felt one wobble or met anyone IN PERSON who has either. I have read about it on the internet but again, have never met anyon in person who has experienced it. Having said all of that, I would recommend you get as new of a bike as you can afford. If you can afford to buy new...buy new. If you can only afford a 2008, buy a 2008.
I tour with a lot of different riders. Some on Goldwings, some on EVOs, some on jap cruisers, some on Ultras, some on trikes. At the end of a long day in the saddle no one is talking about the latest do-dad or gizmo Harley or any other brand has come out with. We are having a few cocktails, a few laughs and sharing some of the sights and experiences of the day. Folks have been touring this great country for more than 100 years on Harleys (and you don't hear stories of frame failures). Go get the one you can afford and hit the road. Its a great way to see the country and build some memories.