Default the united.com website to search for GPU-eligible fares on the advanced search page
Only a subset of the fares offered by United Airlines allow for upgrade via their Global Premier Upgrade (GPU) instruments issued to top elites each year. Add this extension on to your browser and it will automatically fill in the eligible fare classes on the advanced search page, making the search just a wee bit easier.
Combine with the UA Expert Mode+ extension and you can more easily find eligible fares with the upgrade space open, too.
Also has the appropriate fares for Business->First GPUs included.
Latest version updated to support the new United beta site