I thought about drilling in the side, which is what I often do with big container. Problem is, I think both of those are double-walled containers, and with them already planted I don't know how far up the side to start drilling. Also, do we know if the containers will continue to be watered from overhead? If not, the more contact with the ground, the better.
I can do a pilot hole in the side to be sure I'm far enough up and then stick in a wick (microfiber towel strip) that goes into the potting mix and also down under the pot for good soil contact. Or I can just drill them in the bottom. We'll likely move them in fall, and we could easily tilt the containers when planting annuals in spring to be sure roots aren't growing up into them. I don't think tree roots will be a big deal -- I've never heard sycamores were difficult that way, and I didn't see any maple trees nearby.
I'm anticipating that getting watered every day won't continue, and I think drying out is likely to be more of a problem than roots... good ground contact helps, that's why we dug down to place the containers, and bottom holes may be best for that.
Anyway, those are my thoughts on it. I'll drill the holes anywhere you want them. If you want holes above-ground on the sides, that'll give a good 6 inches of "reservoir" inside the pots.