Someone asked me today why a senator who had no intention of voting for a bill would put amendments to the bill in the markup. Aside from the obvious attempts to kill a bill with poison pills or to create fodder for future campaign commercials, the good-will reasons are because that is what good legislators do. They look out for the best interests of their state and they do their best to make good legislation. Very few Republicans are interested in offering good-will amendments, but there are more of them than you might think. In my opinion, Lisa Murkowski made several valuable contributions to the HELP version of the health care bill. Even Tom Coburn made some solid improvements (although he wasted a ton of time with bad-faith amendments, too).
Ezra Klein takes a look at the amendments that Olympia Snowe has submitted to the Finance bill. Now, Snowe may very well vote for the Finance bill, but that is no foregone conclusion. Yet, even if she ultimately declines to support the bill, it will be better because she was involved in the process.
You can use this opportunity to learn a lot about how the Senate really works. What you see on television is 90% posturing.