One of the best day tour in Georgia is to visiting this sites. You can visit cave town Vardzia, then you will visit town Akhaltsikhe with rabat castle, then you will visit SPA town Borjomi, then back to Tbilisi.
Interesting day trip around Tbilisi. You will visit Jvari monastery, then Mtskheta town, then town Gori where you can visit home museum of Joseph Stalin, then Uplistsikhe cave town
Day tour from Tbilisi to wine region. You will visit Signagi love town, then monastery of Bodbe, after drive to winery and trying local wines, then drive back to Tbilisi via beautiful pass called Gombori.
Tours from Yerevan to south part of Armenia are very interesting and especially this one is included Shaki waterfall, Khndzoresk cave city and also Tatev cable car
Armenia day trips from Yerevan is an interesting choice when you would like to see in an one day Christian monasteries, natural beauties, megalithic complexes and a lot of mountains
One day tour from Yerevan to North part of Armenia for visiting 2 monasteries which are included in UNESCO heritage list, and that is Haghpat monastery and Sanahin monastery
most favorite rout in Armenia is tour Garni Geghard lake Sevan and Tsaghkadzor ski resort. This is full day tour and in an one day you will visit Pagan temple, cave monastery and mountainous lake