I totally agree with you about the importance of this basilica not only from an architectural point of view but because of the period that represents and the mosaics are I think its biggest attraction. Regarding your question about the mosaics there are some that caught my eye like the one that presents a clean shaven christ next to San Vitale , bishop Ecclesius and two angels which is the second picture of this post. It caught my eye because of its beauty but also because in my opinion it emphasizes the religious importance of the structure.