Granted, it does have fewer features, but how good are all those whiz-bangs if the battery is dead?
I've been using a Skagen Jorn Hybrid smartwatch for the last few years. No digital display, but the time/date are set via bluetooth, and it has phone call notification, which is mostly what I want. I don't need to read emails or SMSs on my wrist. 6 months of battery life from a replaceable coin cell.
Honestly though, this is the first apple watch to appeal to me. Proper waterproofing, ruggedness, long enough battery life to go away for a weekend without a charger, always on screen. It's almost getting back to where Pebble was - they just need to stretch that battery a bit more with an ultra-low power mode. The cost is fairly high considering the functions I want though, so I'll need to use it in person before I put any money down. I do occasionally scuba dive too, so the dive functionality is actually fairly appealing as I don't own a dive computer any more.
But you don't need 18 days for that. Like I said, I understand wanting a few days. Why do you need a few weeks? It seems like at that point it becomes even more likely that you would forget to charge because it never becomes a routine.