Spending a day in Omsk, 568km southeast of Tyumen, is the best way of breaking a Tobolsk-Tomsk or Tyumen-Novosibirsk train ride into two overnighters. Vast and sprawling, Omsk's industrial suburbs look off-putting but the gently attractive central core has some fine century-old architecture and is dotted with parks, museums, great restaurants and quirky public sculptures.
Tobolsk was once Siberia's capital and remains its most memorable city. Highlights are its handsome kremlin and a charmingly decrepit old town. Tobolsk is off the trans-Siberian mainline but direct overnight trains to both Yekaterinburg and Omsk make stopping here a perfectly viable option when crossing Russia.