[TXPearl]

Sun angle depends on season, latitude and time of day. In my locale, the summer midday sun is almost directly overhead, so I generally park facing eastward if convenient.

[mscot]

they're great for rear passengers. blocks glare and some heat.
I dont leave them up b/c they also block some driver visibility - mostly only an issue in parking lots.
For only $250 they're an easy add on imo.