I traveled to Lappeenranta just for a night and stopped at Cumulus hotel. I checked in “off the street” and got a single smoking room for 84 euro.
Although hotel’s location is great, reception staff was very friendly and helpful my overnight stay was terrible. It was so hot in the room that I could hardly sleep. Better say, I did not sleep at all. Without A/C and {seemed like} very rare airing out the temperature in the room stayed at 25 Celsius all night long despite an open window and outside temperature at 15 Celsius during the night. Polyester bed-sheets did not help either.
Be aware and look for a hotel with A/C in the rooms if you come to Lappeenranta during a hot spell.

Well planted right in the (shopping) center of this charming lakeside town in Eastern Finland and very close to the passenger harbour. Colorful Scandinavian room decoration, simple bathroom, but very nice sauna facilities (separated for men / women) including large indoor pool.

We liked their choice of ham, local and international cheese specialities, Karelian Pirakka, fruits, vegetables, muesli and youghurt at the hot buffet breakfast. We loved their pancakes, but missed maple sirup. We were disappointed about the consistency of their scrambled eggs. Enjoy a summer late-evening sunset beer (local and continental brands) in their Hemingway Restaurant and Bar. Do as the Tsar and visit the museum of the Wolkoff merchant dynasty, showing the career and the home of this Russian immigrator family from 19th and 20th century (one block north of Cumulus)

Ideal stop 200 km east of Helsinki before taking the morning boat thru Saimaa Canal to Russia (Vyborg) and eventually continuing to St. Petersburg (car, bus or train). There are also cheap flights from Helsinki to Lappeenranta.