Need some advice - rescued cichlids, two tanks, what to put where?

I'm hoping to get some advice from the knowledge people who populate this forum...

Here's the situation - a little while ago I was asked to rescue / re-home 10 yellow labidochromis, as the owner was leaving the country... I think they were all purchased together, and they've been living that way in a 10 gallon tank as a nice little community / colony for more than a year now, maybe two or three. They were moved to my place last weekend and have just been settling back into their 10g over the last few days. Seem to be doing fine in terms of appearance, colours etc. They even released some fry during the move, although I made the mistake of putting the fry back into the main tank once they were back so it looks like there's no more fry now :\

Now I've never kept cichlids before except maybe an angel or two and a krib which did fine in my other community tanks... And if it aint broken don't fix it, right? But, from all the reading I've been doing on these guys, 10 gallons seemed like entirely too little space for 10 cichlids, so I've made arrangements to get two larger tanks, one of which is planned for them to move into so they wouldn't be so cramped. The other tank will become a new community tank, an upgrade for one of my older 20 gallons

Anyway, my question is about best conditions for them - a higher tank for more up and down, or a wider tank for more side to side?. The tanks i have available to setup for the labs right now are about the same sizes, either 1.) a 28/29 gal, 30x12x18 (high), or 2.) a 30 gal 36x12x16.

So which one would you use for plants, and which one for the cichlids? Keep the plants in mind as well, would the shorter tank height of the 30 be better for growing plants since the light is a little closer?

I've noticed that these labs love caves and really dig around in the gravel quite a bit so although i'd love to put them in with some of my real plants, I'm not sure that will work out... Instead I was thinking to put them into a tank with medium sized gravel, maybe 5-10 mm in size, as well as some wood, rocks/caves, and fake plants. I'll probably move my 3-4" pleco in with them as well since he's getting to be a decent size and seems to like to disturb my plants quite a bit...

I'd appreciate it if you could provide some advice on tank choice from the perspective of whats best for the labs as well as what's best for the plants. Also any advice on general labidochromis keeping would also help a lot

Thanks

U_E