Is there a convenient way to edit PATH in Windows 7?

There is always the Rapid Environment Editor which claims full support for all major OS versions, including 64-bit.

Editable tree

Show environment variables and values as an editable tree.

Portable mode

RapidEE doesn't require installation and could be run as a "portable application". View details.

There is also the older (but still useful) and more light-weight Path Editor. (Note that the site is dead as of 2015-08-07, but still exists as an archive.org snapshot from 2013-03-27 — direct link to the installer). It works just fine on Windows 7 and, though it comes only as an installer, also works as a portable/stand-alone executable if you extract it.

Path Editor is a small utility that makes path management very straightforward with its intuitive user interface and drag-and-drop simplicity. Path Editor can clean your path of missing and duplicate entries with a single click of the mouse.

Here's another Windows Path Editor:

(Disclaimer: I made this. It's open source, contributions welcome!)

This is implemented in the Windows 10 update released on November 2015.

I understand the question specifically calls for a Windows 7 solution. However, I've posted this answer for the benefit of users who happen to come across this question.

Windows 10, in preview build 10565 and release build 10586 (November 2015 update), has an overhauled environment variable editor which dramatically eases editing PATH.