Great to have to old friends to drink with!
Dalwhinnie is a very easy dram to power through, for me too. I'm not a huge fan of where Macallan is right now.
When I taste old Macallan, stuff made 30 plus years ago, the spirit is of far superior quality to what younger expressions are now. I read all their propaganda about cask selection, narrow cut... but anything made in the last 20-25 years doesn't match the quality of what older bottles offer. About six months ago I had their 12 year from a bottle bottled about 35 years ago right next to their 12 bottled recently. Both bottles were opened at the same time for the tasting, and the older bottle was absolutely a better dram. They two were tasted double blind - meaning, of the 10 of us that tasted them, we didn't know what was being poured and in what order they were served. We actually had them side by side but they were placed in different order in front of the tasters; some had the old bottle on the right and some had it on the left and none of us knew ahead of time either were Macallan. Ten out of ten people picked the older bottling over the younger bottling and the experience of the tasters ranged from novice to industry pros. It was very enlightening and confirmed the opinion I've had about Macallan for about four years now. If you're wondering, three of the 10 of us (I was one of the three) recognized the whiskies were Macallan before they were unveiled.
As for recommendations in your price ranges, I'd just suggest that price not be your guide and to just try a lot of different whiskies. Get into the independent bottlers, single cask, cask strength and unchillfiltered whiskies. This is where the most unique whiskies are generally coming from, in my humble opinion, and I think they'll be impressive to your friends because they likely will not have heard of them or had them. They've all surely had most of the major brands so go lesser known. That said, Glenfarclas cask strength, Highland Park, Springbank and a handful of other official bottlings are really top-notch.
I had a customer bring me a sample of Kilchoman 4 year that was a unique bottling for the Tokyo International Bar Show. It was cask strength and bottled at 60%. Very interesting! Cannot wait to see some older expressions from them!!! It was so well balanced that it needed no water, even at this strength. One of the five-best drams I've had this year (I have had over 250 different whiskies so far in 2012).
Anyway, good drinking!