I know you say you have a clearer idea about what you want to get, but I have been through this too (so many of us have) so I at least want to give you my $.02 worth of advice
If you are leaning towards a Speedy B, you will get the lovely iconic bag with the additional strap. One of the things I love about the Speedy (and Alma too) in particular are the handles. The handles are perhaps my favorite part of the Speedy...their shape, the color as it patinas, the sounds they make against the canvas.
Also the canvas of the Speedy is something that will conform according to how you use the bag, as the Speedy is not as structured as some of the other bags. But the canvas is soft and will develop a character of its own alongside the vachetta.
I do not yet own an Eva but it is on my short list of LV bags I want to eventually buy, for a few reasons: it is elegant and multi-purposeful. It is a clutch, a cross-body, and can be used as a pouch in bigger bags. It looks good with a casual outfit as well as a dressier outfit. It fits enough to handle daily needs, not just for special occasions. If you get the Eva, you will have enough money (or just about) to also purchase a Cles or a Mini Pochette as well.
For me, if I'm ready to spend $1000 on a handbag, if I *really* wanted the Speedy B, I would wait until I had the rest of the money to buy it. Because that bag will hold so much and go with so many outfits.
But if I had money burning a hole in my pocket (not saying you do; just talking about me here) I would get the Eva and maybe an SLG to go with it.
Good luck! Hope this made sense