Strategic value of particular tiles

I felt that Civilization, and other games, do not adequately reflect the strategic value of certain tiles.

Landforms of strategic value, and how to make them more valuable in-game

Isthmuses (e.g. Suez)

Make supply by sea more difficult (this is done well in Advanced Tactics).

Straits (e.g. Gibraltar)

Ability for (advanced) land units to harass shipping trying to pass through the strait. This depends on the width of the strait and the range of weaponry.

Mountain passes (e.g.Khyber pass)

Make traversing mountains, and supplying over mountains, more difficult (this is done well in Advanced Tactics).

Oases (e.g. )

Make trade and military supply over deserts without sufficient oases impossible, giving those in control of the oases control of the trade and military conquest.

Mid-ocean islands (e.g. Diego Garcia, Hawaii)

(Act as supply stations for trans-oceanic voyages, act a military bases from which to project military force and protect sea lanes)

Require ships to come to port to resupply (as in Advanced Tactics)