I've operated only into JNU and even at that I didn't spend more than one hour on the ground so I can't really speak on accomdations or where to go. I will say that the FBO was very helpful.
You're right about the LDAs, except that JNU also has an NDB and SIT has VOR, NDB and GPS approaches.
The weather in all of southeast Alaska this time of year can be rainy with low clouds and fog. Although both Juneau and Ketchikan had sun and 23C today I wouldn't count on it.
And of course if the wind is more than 30 knots you can expect severe turbulence. Field elevation may be sea level but this is just like Aspen or Vail without the density altitude problems.
The biggest concern on the LDA at JNU are the stepdowns (7). Pay attention to how your DME is set. More than one airplane has balled it up at JNU due to improperly set DME. You'll start at 10,000' and stepdown to 1000' (MDA) for the Special LDA-2. For the published LDA-1 the MDA is 2880' (Cat C). Funny thing at the MAP is the non-standard lead-in lights pointing the way to the runway. Also the VASI are offset to be aligned
with the final approach course (not the rwy centerline). This is no big deal if you've done some research.
The big deal at JNU, in my opinion, is the departure procedure. Basically you have to track outbound on the localizer making sure you're meeting the climb gradients. If you depart Rwy 26, this is not a big problem. If you depart Rwy 8 you must swing a 180 in a narrow little channel and remain in VMC over the airport until you're established on the LOC outbound. It can be quite hairy if the ceiling is low with mist and gusty conditions. You may even want to accept a tailwind on departure so that you don't have to swing this manuever. To be perfectly honest, the first time I tried this I was irritated with myself for not becoming more familiar with it in more favorable conditions.
Anyway...Also be on the look-out for VFR traffic on the LOC. Lots of seaplane activity and they use a parallel waterway almost adjacent to the main runway.
SIT on the other hand doesn't have as many perilous stepdowns but it's screwy because this LDA approach is offset only 1 degree. You might think that would qualify it for a LOC approach but it's because (and this took me a year to discover) the final approach course is
parallel to and 350' right of runway centerline!
The DP here is a little more straight-forward. But, again, I have never been to SIT. I'm only familiar with it because we use it as an alternate when we head to the southeast.
Enjoy your trip and let us know how it went.
Here are a couple links to help you out:
JNU info
SIT info
Hope it helps.
Fly safe