Booking a trip with miles NYC-ARN-BER
 

I'd like to book a trip using my MR or UR points (have slightly over 100K on each), but am trying to construct a three way trip NYC - ARN (stockholm) - BER. Any advice on what airline to look at to avoid hefty charges? TIA.

and back to nyc?

Yes, back to NYC.
 

And if Stockholm is not an easy stop, what other european city would make sence for a quick stopover?

What class of service are you looking for?

For non-stop flights I would look into United flights booked through ANA by transferring MR points to ANA. SK and UA flies on the route and they have very different award seat release patterns. With SK you have to pay a lot of taxes but with UA you will be in the clear. Check out http://thepointsguy.com/2013/04/ana-...rtner-roundup/ .

If you need SK flights, then I would look at your UR points transferred to UA. Slightly more points, but no fuel surcharges on SK. If you want business class flights, then look at SK via OSL, or really any flight to europe connecting up with short SK flights. On your way out of germany you can also consider flights out of Stuttgart, Hamburg, Frankfurt, etc. all fairly easy to reach from Berlin via train.

Delta might also fly to ARN, but I am not sure.

Not sure if the points will transfer, but Norweigan Airlines runs nonstop red-eyes from JFK-ARN about 3x or 4 weekly in the summer. It's a budget airline, but if you're looking for cheap no frills, the price was right when I used them for my Stockholm flight.

Use your UR points on UA. UA flies a daily nonstop EWR-ARN. From ARN, I'm guessing you can fly SK to BER (though Berlin is actually a tough city to connect to for some strange reason). If you book this as a roundtrip using UA miles, you can have a stopover in ARN at no charge. Connecting back out of BER, your easiest option will be through FRA, but there will be other options as well, including MUC, ZRH, VIE, BRU, and CPH.