First you have another choice (which I've done for a safari). You can fly into Nairobi and then take one of the small shuttle buses to Arusha and to JRO.

The little buses take a while and you end up with overnights in Nairobi, but they are relatively cheap. see this, http://www.riverside-shuttle.com/index.htm and this http://www.kilimanjaroshuttles.com/index.htm

The trip from Nairobi to the mountain by bus takes about as long as from DAR to the mountain and it may even be shorter from Nairobi.
See http://www.scandinaviagroup.com/Scan...dararusha.html

But the biggest advantage of going through Kenya is you end up with lots more choices for frequent flyer programs because a lot more airlines fly to Kenya than fly to Tanzania. (I flew Swiss International on United miles). Especially from the DC area, there are a lot more opportunities to fly United or US airways to get miles that will get you to Kenya then there are to fly Delta flights that will get you on KLM.

Ths has been discussed before in the "Travel and Dining: Destination: The World. Africa section" in several threads. You'll find a lot more info there.

By the way, you'd be crazy to go that far without also doing a safari. They don't have to be expensive

Oh by the way. Getting frequent flyer flights in August may not be the easiest thing in the world to do. You might want to check availability before racking up a lot of miles. There may be other alternative ways to get the trip done through credit card purchases, than doing miles.