I absolutely hate how Safari handles tabs in Safari 8, and this is absolutely the reason why. It used to be you'd get a drop down button on the right hand side when you needed to look at tabs that couldn't fit. Now you're forced to scroll through individual tabs until you find the one you're looking for.
That's funny, as I hated the way the old version of Safari gave you the drop down thingy when you had too many tabs open. I really like how the new version of Safari (8.0) handles tabs. I have my Performance Mouse MX set up to go through the tabs when you press sideways on the scroll wheel. Works a treat!