  The generation-defining Vera C. Rubin Observatory will make state-of-the-art
measurements of both the static and transient universe through its Legacy
Survey for Space and Time (LSST). With such capabilities, it is immensely
challenging to optimize the LSST observing strategy across the survey's wide
range of science drivers. Many aspects of the LSST observing strategy relevant
to the LSST Dark Energy Science Collaboration, such as survey footprint
definition, single visit exposure time and the cadence of repeat visits in
different filters, are yet to be finalized. Here, we present metrics used to
assess the impact of observing strategy on the cosmological probes considered
most sensitive to survey design; these are large-scale structure, weak lensing,
type Ia supernovae, kilonovae and strong lens systems (as well as photometric
redshifts, which enable many of these probes). We evaluate these metrics for
over 100 different simulated potential survey designs. Our results show that
multiple observing strategy decisions can profoundly impact cosmological
constraints with LSST; these include adjusting the survey footprint, ensuring
repeat nightly visits are taken in different filters and enforcing regular
cadence. We provide public code for our metrics, which makes them readily
available for evaluating further modifications to the survey design. We
conclude with a set of recommendations and highlight observing strategy factors
that require further research.
