my kids ran thru my rose bushes.. ONLY ONCE ... i would not opt out of something just cuz of the kids ... they learn real fast ....

GG's are way to huge..

i would recommend Thuja occidentalis 'Degroot's Spire', for thinness.. though it is still an arb ... copy/paste this link:

https://www.google.com/search?q=Thuja+occ+de+groots+spire&client=firefox-a&rls=org.mozilla:en-US:official&channel=rcs&hl=en&source=lnms&tbm=isch&sa=X&ei=KSUuUqrLCYbuyAHxjYG4Bg&ved=0CAkQ_AUoAQ&biw=1274&bih=810

conifers are trees.. they never really stop growing.. ALL size estimates are at 10 years.. which is 10 years of its annual growth rate .... and one can presume.. they will be twice as big in 20 ...

i premise any of my info with the caveat i know nothing about your zone ...

you said: 4) Something that can deal with moisture

thats cryptic ... with PROPER PLANTING... it is not an issue ... short of being a real bog .... the issue is PROPER drainage.. and secondarily.. perhaps.. non-draining soils like clay ... read up about such at the link ... dig a hole.. and give us some real facts about this ....... why is there water there????

i dont want you making bad decisions based on things that should not be a variable ...

and finally: 5) Something that can deal with limited sun

this weekend [or any sunny day if you are a stay at home] .. you and a timer.. and go out there every single hour.. and tell us EXACTLY HOW MANY HOURS of sun ..... no guessing... part shade.. means absolutely nothing... and also explain .... how deep the shade is .... very bright to cave like.... also list what is growing there now.. that is an indicator ...

we need more facts ... to move on with the analysis ....

welcome...

ken

Here is a link that might be useful: link

Degroots's Spire is my pick too, however your landscaper is totally wrong about Yews. They'd do extremely well in that location.

Dax