Hi StarryK --
Good question. I find myself thinking about how I use VGHD as well, and what could be done to make it more enjoyable pretty often, so here are my experiences and thoughts (some of which will repeat ideas that I've posted in other forums, but which generally don't generate much discussion...).
I tend to have VGHD on while I'm working on tedious things late at night. What I like about the "on your desktop" experience is that it's possible to get things done while also watching clips, which I find not to be true with normal videos and pictures.
I used to dial up the heat as an evening went on, but now tend to keep it on random just to keep things interesting. Sometimes if I really need to concentrate more on work, I'll only click on the bottom two settings and if I'm wrapping up the evening, I'll click the top two.
Once my collection got large (500 cards), I have to say that my enjoyment of VGHD has, ironically, gone down a bit, and the reasons for this are simple. I really like VGHD's choice to play clips randomly and not in any particular order, and I like the unpredictability of the software, but the trouble is that with a truly large collection, it can take 5-10 minutes to click through the model list and select a particular set of cards you'd like. And if a model flips up that you'd like to see more of, your options are limited as to how to make that happen without going back to the console, searching for her, and disabling everyone else (which is to say, you can watch her hottest clips, but there are only so many of those, and lots of other worthwhile clips as well).
So, the first thing I would like is a "tags" system similar to what gmail uses where each card would support a number of tags. Some tags should be things like the model's name, while others might be the categories like VGHD lists on the website (but not as part of the program itself). And you should be able to create new tags, and to enable or disable based on multiple tags (so for example you could hit the "blondes" tag and "natural breasts" tag to get all the cards that fit into those categories or remove the "Sarah" tag if you didn't want to see any of her shows in that particular sitting. This would save a lot of time selecting a group of cards to watch without scrolling through the very long list of models.
Next, anything that requires me to go back to the console annoys me -- the console is clunky and it breaks up that experience of "on your desktop". So, in the same spirit as the "replay this clip when finished" option, there should be choices to "keep playing this card" (which would play clips from the current card until it's unchecked) or "keep playing this model" (which would play clips from all cards by the current model until unchecked). I'd also like options not just to jump to the hottest cards by a model (as there currently is), but also to show the current level of the card and to jump to hotter/cooler levels of that same card so that you could surf through the card a bit interactively without having to go back to the console. This would make being on random with 500 cards much more enjoyable because when a model's card flits by that catches your eye on a given night, you could stick with her for awhile rather than (a) going to the console or (b) waiting for that 1/500 chance to come up again.
VGHD is good, but with these features, I think it would be really, really great, and much more satisfying for long-time members with large collections.