You need a measured floorplan to know for sure if it will work. 2 chairs + side table + 6' circulation on both sides + 2 couches is a LOT of room . Unless you have length to spread out the chairs and sofas, things will be too close together.

Since comfort is the most important thing for your needs, you need to go physically to stores and sit on the sofas to find the one that is most comfortable for your needs. Everything about the construction and even style of a sofa will impact how an individual perceives it as "comfortable". The height, the depth of the seat, the height of the back, the materials used for cushions and pillows - even whether it has coils or is higher quality construction all have impact. It is odd that you found a sleeper sofa to be very comfortable as they are generally a compromise in comfort for most people as they have them for function but give up a certain level of comfort. If you have questions about the "quality" of specific brands of sofa that would be different since that is more or less objective.

I think pictures would be necessary as advised. However even without pictures I agree that two non-matching sofas isn't ordinarily what is done unless both sofas are deliberately chosen for a specific design effect. However ordinarily they would just look odd and random. Also I question why you need an additional sofa for your seating needs. Most sofas only really seat two people comfortably because no one really wants to sit in the middle seat. You can use two occasional chairs and they would provide comfortable seating AND would look like it was more of a planned design since it is not unusual to have two matching occasional chairs, a sofa AND another "solo" chair that complements and ties together the other choices.

It's great that you're making the most of your living space with both a new sectional and your old couch. To blend them seamlessly, here are a few ideas: 1. Color Coordination: Consider adding throw pillows or blankets that incorporate colors from both your new sectional and old couch. This can help create a unified color scheme. 2. Arrangement: Experiment with the arrangement of your furniture. Placing the old couch at an angle or perpendicular to the new sectional can visually bridge the gap and make the space feel more connected. If you're interested in exploring more about furniture, check out this l shaped couch. With a little creativity and some thoughtful design choices, you can create a living space that seamlessly integrates your new and old furniture, making it both inviting and functional.