Ski, I am sorry to hear you and your wife are going through this.
I agree with others here of the need to balance something to look forward to/return to 'real' life with being aware that not everyone follows a pre-determined path in recovery. I've seen a lot of women go through the process of having mastectomies with reconstruction, being one of those high-riskers due to family history and hanging out with a lot of others like me. It never ceases to amaze me how variable people's recoveries are and how no two journeys are alike.
First thing is, though, mastectomy (on its own, without reconstruction) is apparently one of the more 'simple' surgeries . There's no going into body cavities, and it's a relatively quick procedure. So much so that a tactless former nurse friend just couldn't understand why I was in any pain at all after mine. So all going well, it can be at the straightforward end of things, physically speaking. Emotionally...another story.
It's also really important to consider what can (in the unlikely event of...) go wrong. I was like your wife, ready to briskly move through this messy and annoying point in time to get to the other side and get on. My one big surgery (Mx plus starter implants) followed by one more planned one (to get permanent implants) turned a standard 6 week recovery into a 2 year ordeal of infection, more surgeries and some sort of weird allergic type reaction. All the will in the world couldn't have got me on a plane for anything but work travel over that time. I don't recall how long it was before we holidayed - maybe a year after the first surgery, and nine months after the third or fourth?
Four months after the one that went wrong and the one after that and a couple of months after the one to remove the implants I was able to travel domestically for work with a PIC line in and carrying my own little pouches of antibiotics that they taught me to change myself. But medical staff were wary....said most people in my situation were quietly at home waiting for the district nurse to come each day. And yes, it was exhausting and probably stupid....I did notice a lot of swelling and redness at the end of a long day when I was tired, and I am sure it impeded my recovery.
Two years on and eight weeks after a 14 hour surgery to rebuild my breasts again we took a trip to NY with friends (a twelve hour + 6 hour flight) and I flew down to Florida for a conference (so another 5 - 6 hours?) and back across to LAX. Flying no problem, though I did have lymphedema concerns and the redness and swelling (that is something to definitely check out before you travel) again.
It was a trip planned from my hospital bed the day after surgery and eight weeks seemed like ample time. But this time I had fluid buildup that required syringing out most days, right up to a week before we left and I had pulled the stitches trying to hoist myself up out of a chair too fast so had a lot of pain. Still, we went. I couldn't get travel insurance (and still can't for anything breast surgery/cancer related). It was a miserable trip for me - I was exhausted, couldn't keep up with my husband and friends, got a raging UTI and felt like a flake for not being able to get through the days. Again, all the will in the world...
And then again, all the people I see who sail through like text book 6-weekers and life goes on without a blip.
So things to consider:
Travel insurance - you might find it hard to get coverage for any post surgical issues so be 100% that things are as stable as they can be before you leave, if it's an international trip.
Best laid plans - whoever, whatever, however your wife is pre-surgery may not be who she is for a time, post- surgery. As a normally strong, independent, capable person I was shocked at how much it slowed me down and even stopped me for a (longer than usual) time. My interests narrowed accordingly. At times I was happy just to be able to walk to the letterbox, a walk down an airbridge was the last thing on my mind.
Goals matter - it's great to plan a return to real life and have something to look forward to, but make sure it's 100% flexible or things could get very expensive...
YMMV - medical 'estimates' on time for recovery etc are sort of predicated on a normal person leading a normal life. They certainly didn't account for the sort of high octane life I live on a day to day basis, and they don't account for every kind of holiday (lying on the beach is very different to racing around NY, Florida and LAX like the energiser bunny.)
BC surgery specific concerns - like Lymph. really need checking out, pre departure. Mine never came to anything major, but boy, I've seen some horror stories. You don't want to aggravate that monster any more than is absolutely necessary. Also, lingering pain and discomfort issues are worth thinking about. I ended up requesting an extra mattress for the flat bed flights (back then the mattresses were thin) because the surface just felt too hard in places. Had never been bothered by mattress thin ness in the past.
Plan for the worst case scenario, hope for the best - I don't know if your wife is anything like me, but it really knocked me to be in NY and not be able to really enjoy it or even participate for a whole day. I would def. have chosen a different sort of post surgical trip - or taken a shorter hop (maybe to Melbourne for a long weekend) first as a sort of a trial, to check I was up to it. Or gone for a beach holiday first off and worked my way up to the big time.
Anyway - hope some of that helps. Please feel free to PM me if you want, more than happy to answer any questions. All the best with the surgery (I'm the 1% where everything goes absolutely wrong - I am sure it will all go swimmingly) and I hope for a swift and uneventful recovery for your wife.