Las Sendas is a VERY nice district. I wouldn't mind living there myself. Check Dori out; w/God's Blessings.
There is no reason why you need to travel to sign a Lease. If you were buying I would suggest the trip.
The Property owner or management company should be able to e-mail the Lease Agreement to you and you can print it, sign it, and Fax it back.
Question: WHY do you want to come here in May-July? You realize these are our warmest months?
As to the house you have selected to lease, are you doing this through a property management company? Can they send you photos of the house and the area?
Feel free to contact me if you would like an independent take on the house and location.
You could either set up a power of attorney with someone local. Or, I don't see any reason why docs are just faxed back and forth to you in NY. Although I have yet to lease something to someone completely sight unseen, I have represented many landlords that I've never met, including those from NY....not reason you would need to travel here just to sign a lease.