I have a LOT of dives a the BH. I generally go about 6 times a year as I always get the ich to dive, and there is really not much to scratch it with other then Santa Rosa, or a bunch of $$$/Travel.
I also enjoy Perch Lake quite a bit, and have a bunch of dives there as well. One tip with Perch, Rim it! Vis can get quite bad in the summer, but if you stay around 30~45' in the weeds around the rim, the dive tends to be more enjoyable. There are a lot of funky rock formations in Perch, and there are a bunch of fish.
Rock Lake is an interesting dive, but access is rather restricted (think training classes). It is close to 300' deep, and the walls are near vertical. There are sponges in both Rock Lake and Perch Lake.
All three lakes are fed from below, and they all stay well above freezing year around regardless of the outside temps with BH having hardly any temp variation throughout the year.
The best way I find to justify the trip is to enjoy the trip. Go down and room with people you enjoy (my wife does not dive, but yours does!). We generally have a few beers or mixed drinks in the evening, and stay up gabbing.
Don't plan on a rigid schedule.... just go with whatever happens. We don't generally get to the Hole much before 9:00am, IOW's we sleep in a bit. If the hole is crowded, we sometimes immediately go to Perch. We tend to do night dives both nights, and those IMO are the most enjoyable of dives.
The Hole is going to be the most crowded between 8am~2pm Saturday, and 8am~11am Sunday. If we are lucky, we may be by ourselves in the Hole on Friday evening, and that is NICE! It also happens a lot more in winter then other times.
The BH is empty for the most part on weekdays with the exception of Friday evening. Air could be an issue as Stella only works weekends in general. Sunday afternoon is also a good time, as it is empty for the most part.
If you want to do training, go for it! I am kinda done with training for the most part unless I decide to go Pro, or Tech. All my diving at BH is for enjoyment, and very few folks make that claim. 95% of the people there are students, DM candidates, or instructors.
Exposure protection is an issue at all three lakes. Most I know that dive these with any type of regularity do so dry. A 7mm is adequate for any Santa Rosa lake at any time of the year, but Surface intervals can get quite cold in a wetsuit in the winter.
Don't expect too much, and you will never be disappointed.