I think the best route is to wait to get the new plants until you get back. Less worries for you while on vacation. Plants can get uprooted and if theirs little attention paid to the tank, the plants may die after floating around for 3-4 weeks.
However, if it were me, I would get the plants, because I might spend all my plant money while on vacation. If I could stash away 200 bucks in a safe, that would assure I will get the plants and have a nice vacation.
I know how I'm handling my week in the sticks. Doing all the maintenance the night before. This is a water change test and algae scrape of the glass. The new heater will go in a few days before so I can level off the temps at 80. I'll be putting the lights on a timer and calling in a feeding order every day.
Last time I went away, and I was leaving for Vegas every few weeks, the fish were basically left alone. Not going to let that happen again. Took them a week to get back into normal ground.
It's a cruel question to ask of poor folks like me. I tend to want the cake and a chance to eat it too.
