Someone who drives as much as the OP does is able to stretch oil change intervals to a greater extent than someone who does a lot of local, short-hop driving. The Subaru Maintenance Schedule (which should be sitting in the OP's glove box, apparently un-read) specifies 7,500 mile oil change intervals for this engine.
However, unless the OP is using synthetic oil, I would suggest that he/she aim for no more than a 5k mile interval--if this car is going to be kept for the long term. Yes, you can go 7,500 miles, but my personal feeling is that this is only a good idea for the owner who plans to get rid of a car after just a few years.
Anyway, the OP needs to consider another factor, in light of the fact that this is an AWD vehicle.
That is the factor of regular, consistent tire rotations. The mfr's maintenance schedule specifies tire rotation every 7,500 miles, in order to protect the AWD mechanism from damage.
If the OP has his/her oil changed...let's say...every 5k miles, then the tires should be rotated at every oil change. I usually have the oil on my Subarus changed every 4k miles, so I get the tires rotated every second oil change, at ~8k miles. The exact interval for tire rotation is not important, as long as it is consistent, and as long as you don't go as far as...let's say...10k miles, as differences in tread wear can be pronounced by that point.
So--my suggestion is to use one of the following schedules:
Change oil every 4k miles, with tire rotation every other oil change
Change oil every 5k miles, with tire rotation at each oil change
Change oil every 7.5k miles, with tire rotation at each oil change. For this long an interval, I strongly suggest the use of synthetic oil.
But--no matter which interval you choose, make sure that the interval for tire rotation is consistent, otherwise you risk expensive damage to the AWD system, and this damage would not be covered by warranty, as it would constitute owner negligence.
And, please open the glove box, take out the booklet titled Warranty and Maintenance, and begin to follow that carefully. That way, when you are ready for the "big" maintenance intervals at 30k, 60k, 90k, 120k etc, you will be prepared for the long list of services that the dealership recommends, and you won't have to come back here to ask what needs to be done at those intervals.