I was a city letter carrier at usps for 2 years. I was a "T.E." (Transitional Employee) which is equivalent to a ups cover driver. USPS cut our (T.E's) pay $5.90/hr (down to $16.25) and gave us a new title of "CCA" (City Carrier Assistant). I quit a couple months after working at the lower rate. I have been a ups cover driver for 2 years now.
The choice is very easy in my opinion. (If 1. You think you can afford to work a couple days a week or whatever they give you at first as a rural carrier and 2. You don't mind working Saturdays). I would DEFINETELY take the rural carrier job. Rural carriers have it made! They are in a different union than city carriers and get paid by the route, not hourly. They will often be done by 2 or 3 and get paid til 5. Being a city carrier there is a lot of walking, it's a pretty hard job, but rural is completely different...all driving. I tried getting back in as a rural carrier, but let's just say I didn't leave the smartest way and have been black listed apparently. I wish I had the opportunity you do. I hate getting home at 8:00pm. Even though usps screwed me royally, it's a better place to work than ups!!!