I am looking for a roomy two person tent to replace an old two person tent that tapered from 52 inches wide to 42 inches wide. The floor of this tent is quite roomy at 60 inches wide, however, it appears that the wall are not very vertical. Has anyone encountered an issue with the slant of the walls? I am concerned mainly about sleeping space. Thanks.

While this tent is advertised as a 2-person, I have found it to be a bit cramped for two men with just bags/pads and some clothes. It works fine for my wife and I, but not so much when backpacking with a buddy. I'm 6'1", 170 lbs, but with fairly broad shoulders. I'm seriously looking into moving to a 3-person Marmot as there isn't really any weight gain over this tent.

The Twilight is 60" wide at the head, but tapers down to 49" at your feet. Aside from tapered tents, there aren't many out there that are wider than 52" (in the two man category). There are a few at 54" (e.g. North Face Rock 22 Bx) and Big Agnes makes the Salt Creek 2 and Lynx Pass 2 which both come in at 58" wide (although without vertical side walls). You may want to look into three person tents if you think that 52" is a little too narrow for comfort. You may be able to find a two person if you don't mind it tapering down at your feet so that you get a little more width for your torso. Good luck!

I have a Big Agnes tent similar to the Slide, however, the 52 inches wide is just to narrow for my comfort. Hence, I am seeking a wider option.

I don't have any experience with the Marmot Twilight, but I have to recommend the Big Agnes Slide Mountain 2 in this category. The Slide Mountain has nearly vertical walls and around 40" of height. I have comfortably slept two adults and a 50 lb. dog in this tent (I'm 6'3"). It is a little bit lighter than the Twilight and I think the Big Agnes tents use better materials and construction (no offense to Marmot). The Slide Mountain has been discontinued and is on clearance, which makes it $20 more than the Twilight with the footprint. The Slide Mountain also has four mesh pockets built into the corners and an additional two mesh pockets beneath each door. The Slide Mountain uses a BOA system for tightening the rain fly from inside the tent. While a nice feature, it is a little bit gimmicky and was likely the downfall of this tent due to the added cost. I think if you are comfortable with a 2 person tent, and want one with vertical walls, then you can't go wrong with the Slide Mountain 2. You could also look into the Big Agnes Gore Pass 2 which is the same tent minus the BOA rain fly system. It also has a fast pitch option which the Slide Mountain does not.