You may also wish to try a defrag program that has been around a long time as a Pro version. Vopt. It takes the approach of reducing the number of "gaps" between files. I have used it years ago and recently started using it again because the author of the program left instructions that when he passed away Vopt should be distributed as freeware.
Along with basic defrag it does some other things such as defrag of the page file, disk testing using S.M.A.R.T etc..
You can download from Softpedia on this page: Vopt Download
The last version was released in 2009. I have been using it on Windows 8.0 64 bit GPT based HD with no issues.
I'd have to say that the built in-tool (adapted from Diskkeeper) is OK. I like that with the command prompt you can defragment the prefetch and boot stuff. But I find Perfect Disk (v14 is compatible with Windows 8x) works REALLY well. I'd say Piriform's Defraggler is a close second.