Tandem Cycling - How to get my kids to school

So next year, my kids will be at the same school (finally), and I have to drop them both off. My son is 7 and about 60 pounds, and my daughter is 5 and about 40 pounds. The trip from home to school is about a mile, with several hills that are enough to raise a sweat. It's urban so niether kid can ride alone. I foresee ditching the kid transport back at home and riding my own bike to work, so the two-kid transport is mainly for this mile trip (in just about all weather).

I'd love to get a Bike Friday triple, but I think it's out of the question on price. So I was thinking of a Burley trail-a-bike for my daughter (they both have and love trail-a-bikes now) attached to a tandem for me and my son. My thoughts were the Burley Zydeco or the Trek T900. I love the looks of the Kidz Tandem but am concerned about price (mainly) and stability. Ideally, we could keep this arrangement up for 3-5 years. Anyone with thoughts or advice? Thanks!

I have a Burley Piccolo and my daughter and I love it.
We just switched to a regular tandem so we're not using the Burley much.
Again, very good design with clever attachment point on rear rack.

I made the typical "DAD" mistake of riding the tandem to pick up my nearly 18 yr old son from school.

Picture him waiting for me to arrive on my motorcycle at the popular pick up area with loads of cool kids around.....then me arriving on my tandem..... It was the quickest take off and sprint through town we've ever done!!

Zydeco and trail-a-bike should work fine.

can anyone help me find info about a rixe german made tandem. i have pics.
emh1980ohio@yahoo.com

I want to add a thought here. Of course, you mentioned the price of triplets, but if you anticipate using it for a few years, it might not be a bad investment. Every once in a while, used triplets are available. Presuming you can keep it in reasonable shape, you could probably sell it for about the same price (if you ever wanted to sell it). Most of my triplet riding is actually only done with 2 riders, but there is the occassional ride when all 3 of us (wife, daughter, and myself) ride together.

I pick the little one (7 years old) up from school about 3 days a week. I'm fortunate to have a big stairway just outside of my office at work so I actually ride the triplet to work (only 1 mile) and then leave from work to get her. Its 2.5 miles each way, 2 decent hills. Its really not a problem to ride the 60 lbs pound bike by myself to pick her up, and then the two of us ride home. I live in the city and I usually don't have any problems in the traffic. The only annoying part is listening to 100 people/day asking me in jest (I think??) if they can ride on the empty seat.