I always found that while masturbating, if I stop just before ejaculation and wait about a minute then start up again, repeating the process until I can't stand it anymore - generally gives me much more powerful and pleasureful orgasms.
Foreplay with partners has a role in this too I believe, if you 'play' with each other for a period of time (without either one losing interest) it makes the sex exponentially better.
I noticed with my ex-girlfriend, whenever we had sex and I would stop just before she would climax - the end result was much more powerful when I actually did finish her.
I suppose the root chakra kind of acts like a capacitor - the more charge you pump into it (ie keeping the connection open longer and building the desire through foreplay, with yourself or partner) the more energy there is to release - and the more extended (and smooth) that release will be, as evidenced by Christian's multi-day high.
Sometimes it is too easy to get locked into 'masturbation as a habit for relief' rather than a 'ritual for connecting with your sexual power'.