The next time I go there, I'd like to take my time looking at all the books.
The next time I go there, I'd like to look around the store at my leisure.
この場合、次のような言い方ができますよ。
ーThe next time I go there, I'd like to take my time looking at all the books.
「次そこに行ったら、いろんな本を見るのにゆっくり時間をかけたい」
to take one's time で「ゆっくりやる」
ーThe next time I go there, I'd like to look around the store at my leisure.
「次そこに行ったら、ゆっくり店を見てまわりたい」
to look around「見て回る」
at one's leisure「ゆっくり」
ご参考まで!