Some ideas that comes to mind.
Type: maybe something a bit more geometric could help.
When I think of "landscape", I think something mostly horizontal with some vertical elements. Their original logo is too vertical.
They should give you some visuals of their work you could use as inspiration.
If you rotate the k in your last attempt (Box1c) 90° counterclockwise, you have an horizontal landscape with a very abstract (dare I say, architectural) tree in it.

I like Agave 1b.

Maybe something down the organic road, bit scripity/hand rendered. This is a logo of a local council near to me in london that come to mind. pronounced suth-erk.

I think that architecture firm needs more robust/stable/technical logo. Their current logo is nice, stable, square, firm...

To me 2B and 1A seem the most promising. Especially 2B. 1A has too strong an emphasized type and should be loosened a bit. While changing type to normal weight, you could also widen character spacing when using all caps. It could make it even more "posh", because you can afford space. Anyway. I don't think too organic logos will be well accepted by your strictly technical clients.

The mark you have in 2b is better than any of the others. Pardon my harsh criticism, but the mark in 1, 1a & 1b is dreadful.

If you decide to go the plant / leaf route, I get the feeling they'd like something that vibes with this: http://www.behance.net/Gallery/Robinsson-Cravents-Identity/173877 — Geometrical, architectural, and mathematical even.

Thank you all for your input. I definitely think I have too many options on the table because even in 5 responses there is direct opposite views, but I guess that's what makes design so interesting, it's all in the eye of the beholder.

penn & ink, thank you for the directness of what you thought about the mark in 1/1a/1b. Their company tag line is "Imagine. Create. Live." The 3 petals or leaflets were meant to represent each of these in the case that they want to use the mark/icon with just the tag line. Sometimes I find myself getting too caught up in satisfying these types of things and then when all is said and done I stand back and look at the logo and think "what the hell was I thinking?"

As for the client's eye, they are attracted to the horizontal layout of the text in 2b but think "Landscape Architects" is too long to be sharing a single line with "southwick". They also feel like that text arrangement is all too common among architects as well. While they like the horizontal feel in 2b they also dislike the icon in 2b the most of any. They feel it looks like something that represents a hotel/resort or would be found on a complimentary bar of soap...haha, I can't argue that!

They are most attracted to the idea of Agave1c but aren't sold on stacking "landscape" over "architects" on one side like that. They also have concerns about the square fighting for attention with the free flow of the agave plant. Here are some other options on Agave1c that may help resolve those issues.

this is becoming better but as mentioned before in my post (I forgot to say that 1A I was referring to should actually be Box1A because there is more than just one 1A). Anyway.

I would use normal weight Gill Sans in "southwick". The same would then be applied to the box/line that derives it's weight from letter weight.

Plant stylisation may as well be a bit confusing. Lines are also way to thin in some parts. Experiment some more with plant if you really need it. I wouldn't use it anyway. Or make it more "sans serif" with uniweight strokes...

Well, I have met with the client a couple of different times since this update and they have reverted to wanting something more simple. They have thrown out all concepts at this point that have any plant mark involved and would rather stick to holding on to their box of the current logo somehow. They have also come up with a new tag line and would like to see it incorporated with the logo.

I feel like these are too plain now and don't set them apart as anything different. These could be anyone's logo and I am having a hard time believing that after all of this process that these are what they would truly be happy with.

This is a jumble of random elements that don't have anything to do with each other. It looks like you're struggling for ideas. Clear your brain and start fresh.

Do the periods have to be in the 'tagline'? I'm so over that trend of false punctuation. I'd either go with midpoints or nothing at all between them.

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penn