It is a very interesting question indeed.
If Earth rotated like Venus, the day - night variation would be more intense, particularly over land, but as Wayne say's the water from the oceans would evaporated from the day side & would just precipitate out as rain & snow over the colder areas.
The Earth's global thermal inertia would not change, only that it would be distributed differently.
Also Venus's night time surface temoperatures are only 5 C cooler than the dayside. As Wayne also said, that huge chocking, dense CO2 atmosphere is acting as a green house & also the dense cloud layer acts as a stabiliser, preventing a large diurnal difference on Venus.
To cool Venus would involve:
1). Putting a gigantic sun shield in front of the day side of Venus.
& / or,
2). Blasting a huge hole in the clouds over the night hemisphere to radiate excess heat into space.
& / or,
3). Move Venus further from the Sun.
& / or,
4). Somehow bleed some of that atmosphere into space.
& / or,
5). Convert most of that remaining CO2 into Oxygen, using microbes initially.
All five are well beyond today's technical means.
Andrew Brown.