Time to tear down the trip into its component parts.
I expected this trip to be a lot more expensive than usual (even after remembering that the expenses have two people!), and I was right. For comparison, I stumbled across an offer of an almost identical organized trip while researching during our trip. For seven days, covering almost the exact same route we took (if in reverse), visiting almost identical sites (including Coba darn it), traveling by bus with a couple of short day-trip bicycle rides, for 7 nights (we traveled 8), the cost of the organized tour was $1,495 per person (including lunch a few of the days, but not dinners). My more comprehensive estimate for the cost of that guided trip is about $1800 per person, or about $257 / night per person (likely more, as we only splurged for expensive meals a couple of times).
I usually cycle tour for about $40/day, where this trip was $56 / night per person. More expensive than touring, but 21% of the cost of the organized tour. Now, that meant we had to walk to the bus station and buy own own tickets, and I had to reserve the accommodation myself (easy with hostelworld.com). All in all, well worth the organizational effort!
I planned mostly by researching things near Cancún, and then planning nights in places nearby. My regrets for this trip are primarily missing Coba, and over-scheduling ourselves for travel. In hindsight, I also would never have spent a night in Cancún. Instead, I would have spent another night in Vallodolid (visiting more cenotes), and another night in Tulum (visiting Coba). That would have let us visit more things, with two less “travel days,” which we both would have preferred. I was overly cautious in the awareness that I didn’t have a bicycle and couldn’t control my travel to my usual extent. However, in the end the buses and taxis were copious, and easy to arrange.
Packing this time was a matter of pulling out my Gear List and not packing the things specific to cycle touring. Marnie bought a pair of VivoBarefoot Tracker hiking books she was quite pleased with. Overly concerned about the water in Mexico, I picked up a LifeStraw water bottle with included filter for Marnie, as well as a Sawyer Mini Water Filter and a SteriPen UV Water Filter. We were both quite diligent in avoiding the usual risks from contaminated water: not drinking it (obviously), not brushing our teeth with it, not eating salads (often washed in local water), avoiding ice (potentially made from unfiltered water), paying attention to fountain drinks. The combination worked – neither of us had any digestive issues at all.
Marnie used the Lifestraw constantly-that was a great purchase. However, I only used the SteriPen a couple of times to purify fountain drinks. In all of the cases I used the Sawyer filter I had the opportunity to buy bottled water. For the amount of water I drank, bottled water would have been a cheaper option. And using the Sawyer filter was a bit of a hassle, filling up the associated pouch and then squeezing the water through the filter.
Before I left home, I decided that my default withdrawal should be 5000 pesos, or about $250, my usual baseline for cash on hand. Concerned about the exchange rate from the ATM at the airport I only withdrew 3000 pesos, and then for the rest of the trip withdrew money at 3000 pesos at a time which meant I felt like I was spending more money because I was withdrawing money far more often that I anticipated (that combined with not being used to living for two). The ATM fees were about $5/withdrawal.
Mexico (or at least the Cancún region) was solidly cash-based; very few places took VISA directly. However, I never had any significant problem finding an ATM. More significantly, many (but not all) places would accept USD. Now, that local exchange rate varied from 1:20 to 1:10, so your mileage may vary. I’d also suggest if intending to use USD at times to carry a lot of small bills.
All in all, over a week in Mexico for a little over $1000. Despite both of us having colds for part of the trip, we visited four ruins (Chichén Itzá, Ek’ Balam, Tulum, and El Ray) and eight cenotes, as well as a number of other smaller natural and historic sites. I even managed to squeeze a little cycling in!