Increasing the landscape almost always improves the value of a property, but installing a new lawn, new sprinkler system is only adding to your overhead with practically no immediate return. Sprinkler systems require at least 2 maintenance inspections for startup and shutdown, plus the additional increase in your monthly water bill. With the additional water, the lawn will also require more frequent mowing-- more costs!
Provide the maintenance (mowing, etc) required in your leases, but maybe reduce the lawn size and maybe add some low maintenance landscape-size plants to improve the look of the property without increasing your monthly overhead. Just adding some inexpensive mulch to existing flower beds and borders will do wonders without costing a fortune.