Does a list or matrix exist anywhere that shows compability of Shimano road shifters, cassettes, and cranksets?

The reason I ask is that I have a Sora equipped Specialized road bike with the original drivetrain (except for a bottom bracket that I had to replace). The cassette and chain are worn out (after 20,000 miles over past 5 years), my LBS estimated about $200 to replace the cassette, chain, and 2 of the worn chain rings, which doesn't seem bad. But, I plan to keep this bike for a while and would love to upgrade the shifters to either 105 or newest Tiagra- whatever is needed to get away from the dreaded thumb shifter.

So I'd like to follow the LBS advice but also upgrade the shifters if it isn't cost prohibitive (since this is only a ~$900 bike to start with). I can't find anything that would answer this on the Shimano website (and would ask my LBS but am out of the country for several months, and would like to have a plan in place before I get back to the US).

Thanks.

IMO, you will not notice the performance difference between Sora and Tiagra. However, if your intent is to get rid or the thumb shifter thingy, then go ahead. If you go to 105, you'll be changing everything to 10-speed, and get closer-ratio gears.

20,000 miles is pretty good for 5 years. Is there any reason why you wouldn't be shopping for a new bike?

You probably can't or don't want to wait, but 2012/2013 Sora loses the thumb lever and will be like Tiagra, 105, etc. It remains 9-speed. I'm not sure how soon it will be available.

Interceptor- thanks for the chart, exactly what I was looking for, did I just miss it on the Shimano website?

I do intend to go new bike shopping and upgrade significantly. But there's nothing wrong with the frame or rest of the bike, so I will probably make this my bad weather bike.