As a regular at Four Points I would recommend it over Aloft, I'll be checking in on the day you check out

As others have mentioned Aloft is further along Soi 11 and in a more "vibrant" area that is more suited to a couple who want to experience secret cocktail bars (Havana Social, The Photo Booth) and the nightlife in the area.
While there is a Tuk Tuk service provided, depending on time of day it would be quicker to walk to or from the Hotel.
The Four Points is situated roughly half way between Nana and Asoke BTS station... Asoke does seems a lot closer but it is an illusion, yes I have counted out the steps one time when the matter was brought up on another forum

Terminal 21 is attached to Asoke BTS and Sukhumvit MRT is close by.
The Marriott Sukhumvit 57 is also a nice hotel in a "normal" are was it was put, but venture a street or so away and it too is either seedy or vibrant depending on how you view it.
Just realised you will be there during Songkran (13-15th) so expect to get wet, have a dry bag for phone, wallet etc.
If staying at Aloft I would expect the street during the day to be nothing but water fights, at least with Four Points you can use the back entrance to avoid getting too wet though if you plan it correctly back entrance to / from hotel and cut through Robinsons to the BTS will see a high chance of staying dry.