I think some of it depends on your LO's personality. My DS was a fairly portable baby which makes outings very easy. We just have to time it so that he gets a nap in the car or stroller at some point around his usual nap time. And amazingly his naps were of decent lengths, so long that you don't transfer him.
My DD on the other hand is not as portable and naps are always shorter out and about. She is now 17 months old and has a very good routine at daycare/home during the week. On weekends, I love being out and about (mainly for my sanity) so at least one of the two days we go out and I know her sleep schedule will be off, but luckily she gets right back on track after a day or so. Yesterday we were out the entire day and during our long drive to our destination she fell asleep for 20 minutes, which then threw off her nap around noon time. Later in the afternoon, I had to APOP'd a nap in the stroller (by pushing the stroller back and forth) and she did manage an hour nap. Of course she was tired on the drive home so had another cat nap around 6 PM, which threw off bedtime. She ended up sleeping in this morning but then resumed her normal schedule at daycare.
Sometimes friends want to meet for lunch during DD's naptime. I can usually APOP a car nap before lunch, enjoy lunch and then she'll nap again in the car on the way home. Probably not the most ideal in terms of EASY but sometimes you just have to go out and have a social life in order to keep your sanity. Also, I keep reminding myself that naps are only temporary, they will soon outgrow the need for one and life will get easier. And don't be afraid to APOP a nap out and about.