This is simply my own recommendation. In order to run CentOS 7 on the desktop, most folks want stuff you can’t get from CentOS directly.
For example, most of us still use websites that require Flashplayer. Adobe has set up a Yum repository that updates as it should with anything related to Red Hat. Using your CentOS box and your favorite browser, go here. The webpage should detect you’ll be running 64-bit and offer a button with a drop-down — select the YUM version and download. It’s an RPM you can install as root. Run “yum update” and you can then elect to install Flashplayer.
For almost everything else you would use on the desktop, I recommend you add the EPEL and Nux repositories. The quickest and easiest path is go here and read the short explanation. The Nux provider links back to the EPEL release as a prerequisite and puts it all in a simple single CLI copy-n-paste command for you:
(Update: EPEL repository is no longer in beta, so the link changes to this: https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm.)
However, I prefer to download the linked release packages and install from Yum. These release packages will install the repo references to Yum, so run “yum update” again and you are ready. For example, one of the biggest things is adding the necessary packages to run a wider range of multimedia using the default Dragon player on the KDE4 desktop. It uses GStreamer as the backend, so all we need is the rest of the GStreamer plugins:
yum install gstreamer-ffmpeg gstreamer-plugins-bad-nonfree gstreamer-plugins-ugly
You can peruse the list of goodies on Nux and EPEL to see what else you might want. I note that EPEL is still considered a beta repo because they are still working on the packages and the collection itself. That should all update for you automatically once they feel it’s ready. I’m quite certain they’ll add the matching 32-bit packages after CentOS makes that version ready for CentOS 7. However, it’s highly unlikely you’ll need to mix the two architectures unless you just have to run something like Wine to enable running Windows apps.
In other words, using Nux and EPEL on CentOS 7 64-bit just about covers everything you are likely to need and it’s virtually hassle-free. Kudos to EPEL and Nux for the hard work to make us comfortable.
As a side note, building your own stuff from SRPMs requires keeping track of how RHEL/CentOS draws from both FC18 and FC19. I noticed that almost everything KDE is from FC18. I was able to build Bibletime, GKrellM, Xscreensaver (KDE’s screensavers seem perpetually broken in all versions), PySolFC and everything necessary to build them that wasn’t already available from CentOS. It can be time consuming, but you learn an awful lot when chasing the prerequisites through RPMbuild. Please note that you should check the Fedora Updates repository for both FC18 and FC19 as well as the “Everything” list.