you might find you like surface more when you have more modulation and it is more 'in the mix' with more voices
personally I've never used a sequencer for cv - I find lfos, function generators, sample and hold and envelopes work better for me
quantizers are very useful if your main sequencer is not quantized - just like mixers and audio interfaces and vcas - get more channels than you think you need now so that you don't run out quickly in the future!
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities