For Jose Solís and Paul Sherrill, partners in Solís Betancourt, the goal for every interior is a balance between formal and informal, traditional and contemporary, while always keeping comfort and livability in mind. There is a striking simplicity to their arrangement of furniture and art: the look is subtle, never excessive, yet the designers are not afraid to bring in dramatic elements to surprise and enchant the eye. These choices contribute to a look that appears effortless, as though the collection of objects came together little by little over decades.   Most notably in a Solís Betancourt room, comfort centers on the sensuous fabrics that might envelop an armchair, cushion a delicate settee, or softly frame a set of French doors. Fabric might be used as an accent, lining niches or bookcases as a background for the objects on display. Or fabric might take on a more important role, covering the ceiling and walls to create a tactile and alluring environment. Nubby linens, shimmering silks, regal damasks, are subtly layered into a serene composition that begs to be touched and enjoyed.   These are interiors that offer a moment of transcendence, a glimpse beyond everyday routine. These are rooms to come home to, sanctuaries that offer a sense of protection, tranquility, and beauty.