I noted that some you you had Krieger 10L bags on the front of your bikes - how did that work?
I used 3x10L and 1x20L Kriega bags plus the 25L backpack on Turismo.
The backpack was awesome but not even close to waterproof (note they have since released a 30L pack with waterproof components), I didn't even notice it was there most of the time (I do wear a back protector though).
The 20L bag I had strapped onto the pillion pad and you can strap 1, 2 or 3 (I think) additional 10 bags to it ... you will need to make sure you avoid your pipe on the right if you go 10+20+10. There was enough room for the 20L bag without hanging over the tail light and you could still fit on the seat. The bags have a rubber-mesh on their underside but I found the 20 had a few hard bits that can mark up your seat - it should be noted that I was using the virgins (saddle box seat) which has a hard surface so it looks a bit marked. Also bear in mind we were gone for 3 weeks with all sorts of weather and roads getting in there.
I had one 10L bag mounted on the tank, their tankbag converter covers your fuel cap but unclips and swings out of the way pretty easily. The converter also has a rubber backing but the straps are a bit dicky. The front needs to be looped around your headstock (is that the right term?) so you need to be careful that it is not binding any cables. The back is kinda stupid in that it is held on with some velcro sticky pads ... which I found moved under the constant strain. A couple of cable ties and Bazz's assistance (with his soldering iron) overcame that problem en-route.
I also had two 10L bags strapped to each side of the trellis frame. One could interfere with the throttle if you didn't quite get it right ... but they are pretty fiddly. To thread the straps and buckles takes some time, but it was not a big concern for me as I usually left the straps on when the bike was parked up for the day.
I think this setup provided a pretty balanced weight distribution ... I could notice it when I did a short trip with only one side loaded. The 10 and 20L bags seem to be waterproof (we had some very wet days) but this is due to the 'roll top' ... so it can be a pain in the arse if your enjoying good weather and need to get, say, a camera out - it also wastes a bit of 'bag space'. For access you need to undo 3 buckles and unroll the top of the bag.
You also need to remember that 10L is not a lot of space ... don't expect to be able to fit 'heaps' in there.
All said and done ... the Ventura is the simplest and the space can be huge depending on the bags you choose. It just means that all the weight is behind you ... and the Monster already has a bit of rear-weight-bias.