First, if you haven't been to Alpine Lakes High Camp (formerly Scottish Lakes High Camp), put it on your list of things to do! This is an absolutely wonderful, rustic, charming collection of nine simple cabins (with comfy beds, cookstove, no bathroom though/outhouse) plus a hot tub and sauna (yeahhh!), and a main lodge house for gathering and an occasional Saturday night pot luck. The camp is staffed by 1-2 knowledgeable hosts who can help you with your hiking plans for the day.
We started our hike from High Camp along a dirt road to Picnic Point and then a gradual decent to Lake Julius. The mosquitos were OK as long as you used deet and kept moving. (They were pretty bad at Lake Julius when we stopped.) We then pressed on to Loch Eileen which was stunning and fewer skeeters. The trail to Lake Donald starts at the base of Loch Eileen and can be hard to find. Head up the rocky slope due south from the base/drainage point of Loch Eileen and look for the cairns.
The extra 1/2 mile and 500' is well worth it. Lake Donald is stunning and guaranteed you will hardly see another soul.