title_body: What are some options for alternative contrasts in demonstratives?
upvoted_answer: As the linked WALS chapter already mentions, a common distinction is to contrast near speaker/near listener/distal rather than a simple distance constrast. 
  
  One way to make such as system more "interesting" can be to add additional usages or shades of meaning to the different demonstratives, for example having one be a neutral term and the other one that is only used when specific focus on the distance is desired, or alternatively having a neutral demonstrative in addition to ones overtly marked for distance (the WALS chapter again already has examples of this, mentioning modern Hebrew and Lithuanian respectively). Korafe (TNG, Oro Province PNG) has a 3 demonstratives e, a, o in a speaker/listener/distal system which additionally serve the function of showing emontional evolvement of the speaker in utterance, with a "near listener" being the neutral default, e "near speaker" showing a great deal of involvement and o "distal" showing a desire of the speaker to distance and dissociate him/herself from the utterance1 pp.75-77.
  
  Variables may be paradigmatically overlaid on top of a distance system, e.g. a visibility contrast as seen in Malagasy(Astronesian, Madagascar)2, or may supplement it, for example by having a 3-way proximal/distal/non-visible contrast. Other contrasts than visibility are possible, for example in Fore(TNG, Eastern Higlands Province PNG), which has a 5-way speaker/listener/proximal/medial/distal system, with proximal and distal further exhibiting a 3-way same level/above/below vertical relationship, for a total of 9 different demonstratives1.
  
  Other than overlaying various such contrasts on a system there is also the possibility of instead having a large set of what may be called "positional stems", whith relatively specific semantics such as "up above", "on the beach" or "towards the Siberian mainland" which can then either be used as or derived into demonstratives. The various Yup'ik languages(Eskaleut, Bering Sea area) are an example of languages with a lot of these, and using various specialised and general nominal morphology allows forming demonstrative pronouns and adverbs with meanings such as "the ones up there" or "from the two entities upstairs/on the mountain", though I think there is a fair bit of variation in the actual meaning of the different stems between the different lects and langs. Section III.4 of this document covers them summarily as they are used in Gambell, St. Lawrence Island.
  
  A somewhat similar in result but structureally different approach to this is exemplified by Nasioi(South Bougainville, Bougainville Province PNG), which rather than have a large inventory of deictic stems and a limited set of affixes instead has just one demonstrative stem a~e from which a large number of directional, as well as some nominalising and oblique affixes may derive different demonstratives such as a-un-toom-peto DEM-NOM-down.north-near.movement_toward"that down there, closer, ascending towards us from the north" or e-eʔ-dan-to DEM-INSTR-seaward-far "by going seaward far away (from us)"1.