One leash in each hand normally. With Lily on my right and Scout on my left. When they are "free" out in front they normally keep those positions and have different cues for directionals and going past things as I don't really want to be dragged willy nilly by dogs trying to mark everything we pass. They are super good girls with me, but if we have someone else with us they will test and see what they can get away with.
I can loop both leashes in my left hand and have them heeling or whatever, but it is more comfortable and fair to separate it out by sides. Lily has a lot less frustration that way. I also have Lily jump on landscape features and walk along stuff to get more mental/physical stimulation, so often she'll be out front and Scout will be by my side. Always just use their everyday flat collars and leashes, they are good walkers for me.
Being forced to never leave Scout because of her SA (I can if I have someone to sit with her... which I do a few times a week normally) can be really frustrating at times. I feel it is important and do see a positive difference when each of them and I get quality one on one time. So I work to finagle that somehow. It is a lot more relaxing and bonding to have one on one walks with each of them. Its gotten much easier since my bf is around and Scout's really bonded to him.
If Chicago is visiting, I walk them in shifts. So first Scout and Chico, then Lily and Scout. She is so closely bonded with both of them that... yeah its just easier. Unless I can commandeer someone to help or if my bf is home.
Even years later, when Lynley visits I am fine walking him and both the girls all at once. I usually have his prong on him, but its not needed as much these days as he is getting older.
Adventures with my parent's BC... well its always out on our property so everyone can be off leash safely. Lily huskies, Scout zooms or follows me with her stick, and Will normally walks at my side. He and Lily love to play, so I usually play stick fetch with Scout while they do. Or at least make sure she has a stick in her mouth so she can't get overexcited and bark mindlessly annoying them.
Chico does well out there too. He does the hound thing having to run waaaaaaaaay out, especially since he never really gets to really run at home. If he gets cranky I get him a big bone out of the freezer for his crate.
I don't really let my dogs off leash anywhere but home or very safe areas of the woods (like the huckie patch) anymore. Not because of them, but because of the huge amounts of other people and usually unfriendly animals. Figure we'd best set an example and I feel better having them close where I can protect them.